Measurement apparatus for measuring internal quality of object

ABSTRACT

The present invention relates to an internal quality measuring apparatus for measuring an internal quality of an object, and the apparatus has a conveying device, a detecting device, a light projecting device, a light receiving device, an analyzing device and a pseudo-object member interposing device, and the analyzing device compares light received with a pseudo-object member, with reference data preliminarily stored, and correct a result of the analysis, based thereon.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for measuring an internalquality of such an object as the greengrocery (fruits and vegetables) ona nondestructive basis.

2. Related Background Art

An example of the conventional apparatus for measuring the internalquality of the fruits or vegetables on a non-destructive basis was adevice disclosed, for example, in Japanese Patent Application Laid-OpenNo. 6-213804. The conventional apparatus will be described belowreferring to FIG. 37 and FIG. 38.

In the apparatus illustrated in FIG. 37, light 854 is projected fromlamp 853 toward an object to be inspected (inspected object) 852 such asa mandarin, an orange, an apple, or the like mounted on belt conveyor850 and a spectroscope 858 receives light 856 having been transmitted byand emitted from the inspected object 852. The spectroscope 858 measuresan absorption spectrum of the transmitted light 824 and the internalquality of the inspected object can be determined based on theabsorption spectrum.

With this apparatus, variations occurred in measured values as aplurality of inspected objects 852 on the conveyor 850 were measuredcontinuously. This is conceivably caused by change of a base line (whichis a value as a reference of measurement) of the measured values of thespectroscope with a lapse of measurement time. This change mainlyresults from changes of the spectroscope and the apparatus itself andfrom change in ambient circumstances.

Another device for measuring the internal quality of the fruits orvegetables such as melons or the like on a non-destructive basis was,for example, a device disclosed in Japanese Patent Application Laid-OpenNo. 6-288903. The conventional device will be described below referringto FIG. 39.

In this device, near-infrared light is projected from lamps 876 towardthe inspected object 874 such as a melon or the like mounted on a shieldbasket 872 on belt conveyor 870 and the spectroscope 880 receives lighthaving been transmitted by and emitted from the inspected object 874through optical fiber 878. The spectroscope 880 measures an absorptionspectrum of the transmitted light and the internal quality of theinspected object 880 can be determined based on this absorptionspectrum.

With this device, variations occurred in measured values as a pluralityof inspected objects 874 each mounted on a plurality of shield baskets872 were measured continuously. This is conceivably caused by change ofthe base line (which is a value as a reference or standard ofmeasurement) of the measured values of the spectroscope 880 with a lapseof measurement time. This change mainly results from changes in thespectroscope 880 and in the ambient circumstances.

With the conventional apparatus, however, adjustment (i.e., calibration)of the base line changing with a lapse of measurement time was carriedout only at the start of measurement, so that the variations occurred inthe measured values with progress of measurement with a lapse of time.

On the other hand, for carrying out the calibration in the middle of themeasurement, the conveyor line had to be stopped on every occasion ofcalibration and the measurement also had to be suspended. Therefore, themeasurement time was lengthened for execution of the calibration.

In the apparatus illustrated in FIG. 38, light 862 reflected by halfmirror 860 is projected toward the inspected object 852 mounted on thebelt conveyor 850 and the spectroscope 858 receives light 864 havingbeen reflected by the inspected object 852 and having passed through thehalf mirror 860, whereby the internal quality of the inspected object852 can be determined as in the case of the apparatus of FIG. 37. Inthis device the spectroscope 858 and reference reflecting plate 866 forcalibration are opposed to each other on either side of the beltconveyor 850 and with the reflected light from this reflecting plate 866the calibration can be carried out at a position where the inspectedobject is absent on the conveyor 850.

The calibration according to this method, however, cannot be applied tothe device of FIG. 37 for measuring the light having been transmitted bythe inspected object.

An object of the present invention is, therefore, to provide a devicefor measuring an internal quality of a fruit or vegetable with lighthaving been transmitted by the inspected object, the device beingarranged in such structure that the calibration of the device can becarried out without interruption of the measurement, so as to eliminatethe change of the base line, whereby the internal quality of the fruitor vegetable can be measured accurately.

On the other hand, in the measurement of the internal quality byspectral analysis as described above, it is common practice to projectthe light from the light source such as a halogen lamp or the liketoward the fruit or vegetable, divide the transmitted light through thefruit or vegetable into a plurality of channels having differentwavelengths, convert the intensity of the transmitted light in eachchannel to current, measure the current to detect an absorption spectrumof the fruit or vegetable, and determine a sugariness or the like of thefruit or vegetable, based thereon. In such measurement, it is inevitableto suffer fluctuations of the light source lamp, specifically, temporalchange and deterioration of spectral characteristics (colortemperature), and fluctuations due to environmental change of ambienttemperature or the like on one hand and it is also inevitable toexperience fluctuations and the like due to temporal change orenvironmental change of the measurement system on the other hand, whichresults in causing errors in the measurement.

In order to avoid it, in the case of such measurement, the calibrationof the device is carried out at intervals of a certain time. Thecalibration is carried out by measuring the quantity of the transmittedlight through a predetermined calibration body instead of the fruit orvegetable being an object originally intended to be inspected. A typicalcalibration method is as follows. In each wavelength channel, ameasurement transmittance T is calculated according to the followingequation to effect the calibration:

    T=I.sub.s /I.sub.r

where I_(r) is the intensity of the transmitted light (more exactly,intensity of current converted therefrom) through the calibration bodyand I_(s) is the intensity of the transmitted light (more exactly,intensity of current converted therefrom) of the fruit or vegetable tobe inspected. Namely, a value of transmittance of an inspected object iscalibrated by taking a ratio thereof to the transmittance of thecalibration body, thereby canceling the change of the transmitted lightdue to the variations of the light source and the measurement system.

For more accurate measurement, the transmittance is also sometimescomputed according to the following equation:

    T=(I.sub.s -D)/(I.sub.r -D)

where D is dark current of the measurement system when the input intothe spectroscope is zero.

The calibration body used in such calibration is normally an object withflat absorption characteristics such as an ND filter (neutral densityfilter) or the like. The reason why the light from the light source isnot monitored directly but is monitored through the ND filter on theoccasion of the calibration is that the intensity of light needs to beof a light intensity level close to the intensity of the transmittedlight through actual inspected bodies in order to make the calibrationaccurate. It is, therefore, common practice to select the transmittanceof the ND filter for calibration so that the quantity of the transmittedlight therethrough is within a predetermined range with respect to thequantity of the transmitted light through the actual inspected bodies.

As described above, the calibration is carried out using the calibrationbody such as the ND filter or the like against the various variations ofthe measuring device. However, the fruits or vegetables being actualinspected objects have specific light absorption characteristics,because the principal component thereof is water; whereas the ND filterhas the flat absorption characteristics. Because of this greatdifference in the absorption characteristics, the flat absorptioncharacteristics of the ND filter cannot follow the largely changingabsorption characteristics of the fruits or vegetables, so that theintensity of the transmitted light through the calibration body and theintensity of the transmitted light through the inspected objects becomeheavily different from each other, depending upon the wavelengths, whichposes a problem of failing to effect the calibration with high accuracy.

There are problematic variations during the measurement by infraredspectral analysis, not only on the device side but also on the objectside.

Specifically, the principle of the measurement of the internal qualitysuch as the sugariness, acidity, or the like of the fruits or vegetablesby the infrared spectral analysis is based on the fact that absorptionoccurs at specific wavelengths in the spectrum of transmitted lightbecause of various groups (for example, functional groups such as O--H,C--H, and so on) of components in the fruits or vegetables being theinspected objects. The absorption spectra of the fruits or vegetablesvary depending upon environmental changes of the temperature or the likeand variations also occur in peak wavelengths of absorption by thegroups. This results in introducing errors in the measurement of theinternal quality by the spectral analysis. This is significant,particularly, in the measurement of the acidity of a low-content acid orthe like. The ND filter does not have a variable property of theabsorption characteristics against the environmental change, and thusthe ND filter is inadequate as a calibration body in this aspect, too.

In the conventional measuring apparatus for measuring the internalquality of the fruits or vegetables by spectral analysis, the positionwhere the calibration body is measured is different from the positionwhere the inspected object is measured in the apparatus, which is areason why variations of their absorption spectra measured are notsynchronous.

The present invention provides a correction method which solves theabove problem.

In addition, values of such internal qualities as the sugariness,acidity, grade of maturity, and so on of the fruits or vegetables differdepending upon locations in the fruits or vegetables. It is thusdesirable to project the light toward the central part of the fruit orvegetable, in the apparatus arranged to project the light toward thefruit or vegetable and measure the internal quality thereof with thelight transmitted thereby.

In the conventional example, however, the height of the projection lightsource was fixed, and, therefore, if the sizes of the fruits orvegetables being the inspected objects were different, irradiationpositions were different between large inspected objects and smallinspected objects. Namely, the light was projected toward the centralpart of inspected object with the small inspected objects, whereas thelight was projected to the lower part of inspected object with the largeinspected objects. It was not able to be mentioned that each of theinspected objects was measured under the same conditions.

On the other hand, the measuring device of this type is arranged tomeasure the internal quality of the fruit or vegetable by the absorptionspectrum of the light having been transmitted by the fruit or vegetable,and it is desirable that the absorption spectrum have the intensityenough to implement accurate measurement.

However, the quantity of the light transmitted by the fruits orvegetables under irradiation of the light at constant quantity issometimes very small, depending upon kinds of the fruits or vegetables.In that case the measurement becomes hard. In general, melons,watermelons, etc. transmit the light in small quantity while orangesetc. transmit the light in large quantity. For measuring the internalquality of the fruits or vegetables with the small quantity oftransmitted light, the difference is unlikely to appear amongintensities of the absorption spectra of the respective inspectedobjects and it is thus difficult to implement the measurement by theabsorption spectra.

An object of the present invention is, therefore, to provide a measuringdevice for measuring an internal quality of a fruit or vegetable on anon-destructive basis while projecting light toward the fruit orvegetable, the measuring device being arranged to be capable ofradiating the light to the vicinity of the equator part (an intersectingline between a horizontal plane including the central part of theinspected object and being parallel to the ground and the surface of theinspected object) of the inspected object, irrespective of the size ofthe inspected object and to be capable of changing the quantity of theprojected light toward the fruit or vegetable according to a kind of thefruit or vegetable.

In many non-destructive measuring devices of fruits or vegetables formeasuring the internal quality such as the sugariness, acidity, or thelike of the fruits or vegetables by projecting the light such as thenear-infrared light or the like toward the fruit or vegetable andmeasuring the absorption spectrum of the transmitted light, a pluralityof fruits or vegetables as inspected objects are mounted on a conveyingsystem such as a belt conveyor or the like and the measurement iscarried out successively for the plurality of inspected objects undermovement.

Specifically, located at a certain position in a conveyance path of theconveyor is a measurement unit comprised of a light projecting devicefor projecting the light toward the inspected object and a sensor forreceiving the transmitted light from the inspected object to measure theabsorption spectrum thereof, and the measurement is carried out wheneach inspected object passes the measuring position. Then thesugariness, acidity, or the like of each fruit or vegetable being aninspected object is computed based on the absorption spectrum obtained.

In this measuring device, it is desirable to implement the measurementat the center position of the fruit or vegetable being the inspectedobject in order to realize the measurement with less errors. Among thedevices of this type, devices in such structure that buckets foraccommodating individual inspected objects are provided on the conveyorand that the inspected objects are mounted on the respective buckets,permit easy determination of the correct measurement timing, i.e., easydetermination of the timing when the inspected object passes themeasuring position, because the positions of the inspected objects onthe conveyor are preliminarily determined at the predeterminedpositions. On the other hand, in the case of the fruits or vegetablessuch as oranges or the like where a large amount of inspected objectsneed to be measured, a way of measuring them while such fruits orvegetables being the inspected objects are supplied and mounted atrandom on the flat belt conveyor by automatic supply means or the likeis more useful in terms of measurement efficiency. In cases where theinspected objects are placed at random on the conveyor, it is, however,necessary to substantiate some means for carrying out the measurement atthe correct measurement position, i.e., at the time when the center ofthe inspected object passes the measuring position. The presentinvention provides a method and an apparatus that enable suchmeasurement.

When the fruits or vegetables such as oranges or the like are placed atrandom on the flat conveyor as described above, the inspected objectscould rotate to move on the conveyor in some cases because of theproperty of the shape of the fruits or vegetables close to the sphere.In such cases there arises a problem that it is not clear whether aninspected object leaving the conveyor was measured at the normalposition. The present invention also solves this problem.

Further, the apparatus of this type normally has moving means such as abelt conveyor or the like for continuously moving a plurality of fruitsor vegetables along a conveyance path, a light source disposed at apredetermined position in a conveyance path established by the movingmeans and arranged to project light toward the fruit or vegetable on themoving means, and a light receiving sensor for receiving lighttravelling through the fruit or vegetable, as main components.

The devices conventionally known are generally classified as follows.

1) devices of a type in which the light receiving sensor is located at aposition in a direction approximately equal to the direction of thelight projected from the light source toward the fruit or vegetable ofthe inspected object and in which the measurement is carried out byreceiving scattered and reflected light which penetrates severalmillimeters into the surface of the fruit or vegetable (this type willbe referred to as a reflection type);

2) devices of a type in which the light from the light source (normally,one lamp) is projected from the side to the fruit or vegetable of theinspected object and in which the light receiving sensor is located at aposition where it is opposed to the light source with the fruit orvegetable in between so as to receive the transmitted light (this typewill be referred to as an opposite reception type);

3) devices of a type in which the light source (many lamps in manycases) is located on the side of the fruit or vegetable of the inspectedobject mounted on the shield carrier (or basket), the light is projectedfrom the side, the transmitted light scattered inside the fruit orvegetable and emitted from the bottom is guided from the bottom througha hole bored in the carrier, and the transmitted light is received bythe light receiving sensor disposed below the fruit or vegetable in adirection perpendicular to the direction of the projected light (thistype will be referred to as a lower reception type).

Among these types, the reflection type devices can be used only forlimited kinds of fruits or vegetables suitable for the measurement,because they can obtain only information of the internal quality of theregion from the surface of the inspected fruit up to the depth of aboutseveral millimeters. In order to extract the information of the internalquality of deep part of the fruits or vegetables, it is necessary toselect one of the devices using the transmission methods of 2) and 3)described above.

The devices using the conventional transmission methods described above,however, had the following problems.

In the case of the devices of the opposite reception type, since themeasuring light passes through the lateral diameter of the fruits orvegetables, optical path lengths are considerably long. When theinspected object is one resistant to the transmission of light, such asan apple, a peach, or the like, the light having been transmitted andemitted by the inspected object is very weak, thus posing a problem offailing to capture a signal. Particularly, there also arises a problemthat the light is more unlikely to pass in the long-wavelength regionincluding the spectral absorption important for the measurement of theinternal quality of the fruits or vegetables. The quantity of thetransmitted light can possibly be increased by increasing the quantityof the projected light, but it is difficult to increase the quantity ofthe projected light in the case of the opposite reception type, becausethe light projection system is normally limited to one lamp because ofthe structure.

In contrast with it, in the case of the devices of the lower receptiontype, since the light can be projected from a plurality of directions onthe side of the inspected fruit or vegetable, the quantity of theprojected light can be increased by employing a multiple lamp methodwith plural light sources. Since the transmitted light is guideddownward, optical path lengths inside the fruit or vegetable can beshorter than in the case of the opposite reception type. Therefore, thistype has no problem in terms of the quantity of the transmitted lightand effective measurement can also be carried out for fruits orvegetables unsuitable for the opposite reception type.

In the case of the lower reception type, however, in order to guide thedetected light out of the bottom, it is necessary to use the boredcarriers or to bore holes in the conveyor, which poses a problem thatthe structure of the conveying system becomes complicated. Since theinspected fruits or vegetables have to be mounted as positioned at thepositions of the holes of the conveyor or as positioned on the carriers,there arises a problem that a supply mechanism for mounting the fruitsor vegetables has to be provided or that an operator has to place thefruits or vegetables one by one on the occasion of the measurement. Ineither case the measurement efficiency of the apparatus is lowered andit is a significant problem for the fruit or vegetable internal qualityevaluating apparatus that often needs to continuously measure a lot ofinspected objects.

A further problem is that assembling of the apparatus and labor ofmaintenance thereof become complicated, because the light receivingsensor has to be set below the belt conveyor, i.e., within a loop of thebelt conveyor.

SUMMARY OF THE INVENTION

In order to solve the above problems, an object of the present inventionis to provide a measuring device for measuring an internal quality of anobject, the measuring apparatus comprising conveying means forcontinuously conveying an object, detecting means for detecting aposition of the object mounted on the conveying means, light projectingmeans for projecting measurement light toward the object, lightreceiving means for receiving light having been transmitted through theobject, analyzing means for analyzing the internal quality of the objectwith the light received by the light receiving means, and reference bodyinterposing means for interposing a reference body having apredetermined optical property in an optical path between the lightprojecting means and the light receiving means, wherein the analyzingmeans compares light received with the reference body being interposed,with reference data preliminarily stored, so as to correct a result ofthe analysis.

The other objects of the present invention will become more apparent bythe below description of the embodiments with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram to show the overall structure of the firstembodiment according to the present invention;

FIG. 2 is a schematic diagram to show the structure of a measuringsection of the first embodiment according to the present invention;

FIG. 3 is an enlarged view to show the structure of a filter portion ofthe first embodiment according to the present invention;

FIG. 4A, FIG. 4B, and FIG. 4C are diagrams to show an artificial fruitor vegetable reference body as the first embodiment of the presentinvention, wherein FIG. 4A is a perspective view, FIG. 4B is a sectionalview, and FIG. 4C is a top plan view;

FIG. 5 is a diagram to show the structure near the measurement positionof the measuring device for measuring the internal quality of the fruitor vegetable in the first embodiment of the present invention;

FIG. 6 is a diagram to show time changes of measured acidity of anartificial fruit and an actual fruit in the first embodiment;

FIG. 7 is a diagram to show synchronism of changes of measured acidityagainst environmental change of an artificial fruit object and a realorange in the first embodiment;

FIG. 8 is a schematic structural diagram of the first embodiment of thepresent invention;

FIG. 9 is a perspective view to show the schematic structure of aprojection optical system in the first embodiment of the presentinvention;

FIG. 10 is a top plan view to show the schematic structure of ameasuring device for measuring the sugariness and acidity of oranges asthe first embodiment of the present invention;

FIG. 11 is a side view of the measuring device of FIG. 10;

FIG. 12 is a block diagram of a control system in the measuring deviceof the embodiment;

FIG. 13 is a diagram to show an example of an output signal waveform ofa photoelectric sensor in the measuring device of the embodiment;

FIG. 14 is a flowchart to show the operation of a CPU in the measuringdevice of the embodiment;

FIG. 15 is a schematic diagram to show the overall structure of thesecond embodiment according to the present invention;

FIG. 16 is a schematic diagram to show the overall structure of thethird embodiment according to the present invention;

FIG. 17 is a schematic diagram to show the structure of the measuringsection of the third embodiment according to the present invention;

FIG. 18 is a top plan view of an evaluating device for evaluating theinternal quality of the fruit or vegetable in the sixth embodiment ofthe present invention;

FIG. 19 is a view taken along 19--19 of FIG. 18;

FIG. 20A, FIG. 20B, and FIG. 20C are diagrams to show the structurearound the measurement position of an evaluating device for evaluatingthe internal quality of the fruit or vegetable in the seventh embodimentof the present invention, wherein FIG. 20A is a side view, FIG. 20B is atop plan view, and FIG. 20C is a side view from a directionperpendicular to FIG. 20A;

FIG. 21 is a block diagram to show an example of a control system in thedevice of the seventh embodiment;

FIG. 22A and FIG. 22B are diagrams to show the structure around themeasurement position of an evaluating device for evaluating the internalquality of the fruit or vegetable in the eighth embodiment, wherein FIG.22A is a side view and FIG. 22B is a top plan view;

FIG. 23 is a block diagram to show an example of the control system inthe device of the eighth embodiment;

FIG. 24 is a diagram to show an example of a height sensor which can beused in the device of the eighth embodiment;

FIG. 25 is a side view to show the structure around the measurementposition of an evaluating device for evaluating the internal quality ofthe fruit or vegetable in the ninth embodiment of the present invention;

FIG. 26 is a perspective view to show the structure of shield platesaccording to a modification of the device of the ninth embodiment;

FIG. 27A and FIG. 27B are diagrams to show the schematic structure of atray in an evaluating device for evaluating the internal quality of thefruit or vegetable in the tenth embodiment of the present invention,wherein FIG. 27A is a side view sectioned in part and FIG. 27B is a sideview from a direction perpendicular to FIG. 27A;

FIG. 28A and FIG. 28B are diagrams to show an artificial fruit orvegetable reference body as the eleventh embodiment of the presentinvention, wherein FIG. 28A is a perspective view and FIG. 28B is asectional view;

FIG. 29 is a perspective view to show the structure around themeasurement position of a measuring device for measuring the internalquality of the fruit or vegetable in the eleventh embodiment of thepresent invention;

FIG. 30 is a perspective view to show the structure around themeasurement position of a measuring device for measuring the internalquality of the fruit or vegetable using a plurality of artificial fruitobjects;

FIG. 31 is a diagram to show a spectrum of transmitted light through theartificial fruit reference body of the eleventh embodiment withcomparison to spectra of transmitted light through actual fruits;

FIG. 32A and FIG. 32B are diagrams to show an artificial fruit object asthe twelfth embodiment of the present invention, wherein FIG. 32A is aperspective view and FIG. 32B is a sectional view;

FIG. 33 is a sectional view to show another artificial fruit object asthe thirteenth embodiment of the present invention;

FIG. 34 is a perspective view to show the schematic structure of theprojection optical system in the fourteenth embodiment of the presentinvention;

FIG. 35 is a perspective view to show the schematic structure of theprojection optical system in the fifteenth embodiment of the presentinvention;

FIG. 36 is a sectional view to show an artificial fruit or vegetablereference body as the seventeenth embodiment of the present invention;

FIG. 37 is a schematic diagram to show the structure of a conventionalexample;

FIG. 38 is a schematic diagram to show the structure of anotherconventional example; and

FIG. 39 is a schematic diagram to show the structure of still anotherconventional example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment of the present invention will be described based onFIG. 1 to FIG. 3.

As illustrated in FIG. 1, the device 1 of the present embodiment iscomposed of a belt conveyor 2, a sensor 4, a measuring section 6, and soon.

On the belt conveyor 2 there are inspected objects 8 such as oranges orthe like arranged in the longitudinal direction A of the belt 3 and theinspected objects 8 are moved in the longitudinal direction A. Thesensor 4 and measuring section 6 are disposed in the middle of themoving direction A of the belt 3. The sensor 4 is a photoelectricsensor, which is arranged to project infrared light 10 onto the beltconveyor 2 and measure the reflected light therefrom whereby the sensor4 can obtain information about presence/absence, spacing, and positionof the inspected object 8 on the belt conveyor 2. The measuring section6 is located downstream of the sensor 4 in the moving direction of thebelt conveyor 2 and is arranged to project light toward the inspectedobject and measure the internal quality of the inspected object fromlight outgoing from the inspected object.

The measuring section 6, as illustrated in FIG. 2, is composed of a lamp12, a filter portion 14, a spectroscope 16, a control section 18, anarithmetic operation section 20, and so on.

The lamp 12 is placed so as to be capable of projecting the light fromthe side to almost the whole of the inspected object 8. The light 22projected from the lamp 12 toward the inspected object 8 is one havingwavelengths, for example, in the near-infrared region (650 to 950 nm).After this light is absorbed in part inside the inspected object 8receiving the projected light, transmitted light 24 is emitted from theinspected object 8.

The filter portion 14 is located between the lamp 12 and the inspectedobject 8. The filter portion 14 is composed of a filter 30 consisting ofND filters 26 and a diffused plate 28, as illustrated in FIG. 3, and acalibration driving mechanism 32. The calibration driving mechanism 32is one using a solenoid and is capable of moving the filter 30 in thevertical directions B according to presence/absence of the inspectedobject 8 in the measuring section 6.

The filter 30 is, for example, a stack of three ND filters 26a, 26b, 26cand a diffused plate 28 and planes thereof are perpendicular to theirradiation direction C of the light 22 from the lamp 12 toward theinspected object 8. The ND filters 26 are filters of neutral densities(achromatic colors) which uniformly absorb the incident light 22 at allthe wavelengths and which have the function to reduce the quantity oftransmitted light without changing the wavelength components of theincident light; in the present embodiment, three types of ND filters26a, 26b, 26c having the respective transmittances of 0.1%, 5%, and 20%are stacked in order from the lamp 12 side to the inspected object 8side. The diffused plate 28 is stacked on the inspected object 8 side ofthe ND filter 26c with the transmittance of 20% disposed closest to theinspected object 8 among the three ND filters 26a, 26b, 26c. Thediffused plate 28 can diffusely reflect or diffusely transmit theincident light from the ND filters 26 and emit light in uniform lightquantity throughout the entire surface thereof. The light from the lightsource can be attenuated at a predetermined rate by employing thisstructure for the filter 30, and the base line of the device 1 can becorrected by measuring the light quantity of the attenuated light.

The spectroscope 16 is disposed on an extension line of the optical pathof the light from the lamp 12 to the inspected object 8 and receiveslight from the inspected object 8 or the filter 30. The spectroscope 16is arranged so as to be capable of measuring an absorption spectrum ofthe output light 24 from the inspected object 8 and thereby measuringthe internal quality of the sugariness or the like of the inspectedobject 8, based on the absorption spectrum.

The sensor 4 described above is connected to the control section 18 andthe control section 18 is arranged to be capable of converting the lightquantity of the incident light to the photoelectric sensor 4 to currentby photoelectric conversion and determining whether the inspected object8 is absent or present in the measuring section 6 by determining whetherthe current is larger than a predetermined value, thereby detecting thespacing between inspected objects 8 on the conveyor 3.

Further, the control section 18 is connected to the calibration drivingmechanism 32 and outputs a signal for driving it, to control the drivingof the filter 30.

The calibration driving mechanism 32 drives the filter 30 so as to placeit in the middle of the optical path from the lamp 12 to the inspectedobject 8 when the photoelectric sensor 4 detects that the spacingbetween the inspected objects 8 is larger than the predetermined valueand then a portion corresponding to the spacing between the inspectedobjects 8 goes into the measuring section 6. Then the calibration of thedevice 1 is carried out in this placement state of the filter 30. In theother cases than above, i.e., during periods in which the spacingbetween the inspected objects 8 is less than the predetermined value,the calibration driving mechanism 32 drives the filter 30 so as toretract it from the optical path from the lamp 12 to the inspectedobject 8. In this way, the calibration of the device 1 can be carriedout on arbitrary occasions, not only at the start of the measurement butalso during the measurement, with the light traveling through the filter30, so that the internal quality of the fruits or vegetables can bemeasured more accurately without being affected by the variations of thebase line due to the measurement. The above predetermined value is avalue determined according to the kind of the inspected objects 8, thesize thereof, the measuring speed, etc., which is set by a user of thedevice before the start of the measurement or during the measurement.

The arithmetic operation section 20 is connected to the spectroscope 16and receives an input of the current from the frequency spectrum basedon the transmitted light 24 from the inspected object 8 or current inthe calibration. The arithmetic operation section 20 can measure theinternal quality of the inspected object 8 without influence of thevariations of the base line, the noise of the spectroscope 16, etc.,based on these current values.

With the device in the above structure, when the measurement is carriedout for the inspected objects 8 arranged in the longitudinal direction Aof the belt 3 on the belt conveyor 2, the spacing between the inspectedobjects 8 can be detected and the calibration of the device 1 can beperformed when this spacing is not less than the predetermined value.Therefore, the calibration can be carried out on desired occasions at aplace where the inspected object 8 is absent, not only before the startof the measurement but also even after the start of the measurement, sothat the measurement does not have to be suspended because of thecalibration. Therefore, the internal quality of the fruits or vegetablescan be measured accurately by carrying out the calibration of the device1 for each of the inspected objects 8 without interruption of themeasurement.

Described below is the step of the measurement to measure the internalquality of the fruits or vegetables according to the present embodiment.

First, the calibration of the device 1 and the measurement of darkcurrent are carried out prior to the start of the measurement. Thecalibration is carried out in such a manner that, in a state in whichthe inspected object 8 is absent in the measuring section 6, thecalibration driving mechanism 32 is actuated to position the filter 30in front of the lamp 12 and the spectroscope 16 measures the quantity ofthe light traveling from the lamp 12 through the filter 30 to thespectroscope 16. The quantity of this light is converted to a currentvalue by the spectroscope 16 and this is used as a base line (or areference value) of the measurement of the inspected objects 8. On theother hand, the measurement of dark current is carried out in a state inwhich the external light is completely shut out from the spectroscope16. This can be effected by intercepting the light travelling to thespectroscope 16 with the lamp 12 being in an on state or by keeping thelamp 12 in an off state. The dark current is the current that the device1 itself has in a state in which no light is incident to thespectroscope 16. When a dark current value is subtracted from ameasurement (a current value after photoelectric conversion) thereafterby the spectroscope 16, a current value from which the influence of thenoise of the device etc. is removed can be derived.

The measurement of the internal quality of the inspected object 8 iscarried out when each of the inspected objects 8 placed along thelongitudinal direction of the belt 3 on the belt conveyor 2 reaches themeasuring section 6 with movement of the belt 3. Namely, when aninspected object 8 reaches the measuring section 6, the inspected object8 is irradiated directly with the light from the lamp 12 and emergentlight, after absorbed in part inside the inspected object 8, is incidentto the spectroscope 16. The internal quality of the inspected object 8can be measured based on a frequency spectrum of this light. This isbased on the fact that the profile of the frequency spectrum differsdepending upon components contained in the inspected object 8, becausethere exist frequencies at which the quantity of light is high becauseof the components.

The base line varies with continuation of the measurement. This iscaused by the environmental change of the temperature or the like of thespectroscope 16, the measuring section 6, or the region around them. Thebase line has to be kept always constant in order to obtain accuratemeasured values. In the present embodiment the base line is measured ata position where the spacing between the inspected objects 8 is not lessthan the predetermined value. This value is stored in the arithmeticoperation section 20 connected to the spectroscope 16.

After completion of the calibration and the measurement of the darkcurrent at the start of the measurement, the filter 30 is retracted fromthe optical path from the lamp 12 to the spectroscope 16, so that thelight from the lamp 12 becomes directly incident to the spectroscope 16.When an inspected object 8 moving on the belt reaches the measuringsection 6 in this state, the near-infrared light emitted from the lamp12 is projected directly onto the inspected object 8. The light isabsorbed in part by the inspected object 8 and is then emergent from theinspected object 8 to enter the spectroscope 16. Then the spectroscope16 measures the internal quality of this inspected object 8.

The internal quality of the inspected objects is measured successivelyevery time the inspected object 8 reaches the measuring section 6 inthis way. When during this measurement the photoelectric sensor 4detects that the spacing between the inspected objects 8 is not lessthan the predetermined value, the control section 18 determines that theinspected object 8 is absent in the measuring section 6 and outputs asignal for driving the filter to the calibration driving mechanism 32.In response to this signal, the solenoid of the calibration drivingmechanism 32 is actuated to move and position the filter in the opticalpath from the lamp 12 to the spectroscope 16.

The filter 30 is, for example, a stack of three ND filters and adiffused plate and the ND filters 26 are a stack of three types of NDfilters 26a, 26b, 26c having the respective transmittances of 0.1%, 5%,and 20%, arranged in this order from the lamp side to the inspectedobject 8 side. The light incident to this filter 30 is attenuated by thethree ND filters 26a, 26b, 26c to about 0.001% of the light quantitythereof. On the other hand, the diffused plate 28 is stacked on theinspected object 8 side of the ND filter 26c with the transmittance of20% and the light incident to this diffused plate 28 is emitted in adiffused manner. The light from the light source can be attenuated atthe predetermined rate by employing this structure for the filter 30.The quantity of this attenuated light is adjusted so as to be within apredetermined range against the quantity of the transmitted light by theinspected object 8 such as the orange or the like. Namely, the NDfilters 26 and diffused plate 28 used herein are changed depending uponthe kind, the size, the lot, etc. of the inspected objects 8.

The base line of the device 1 can be measured by measuring the quantityof the attenuated light by this filter. Fluctuations of the base linecan be followed up as occasion may demand. The measured value of thebase line is stored in the arithmetic operation section 20.

Here, the transmittance discussed below is used for the evaluation ofthe internal quality of the inspected objects 8. Specifically, thetransmittance T of each inspected object 8 (the i-th object out of thetotal n) is expressed by the following equation:

    Ti=(Si-D)/(R-D)                                            (1)

where Si is a measured value of the frequency spectrum of the outputlight absorbed in part within the inspected object 8, R is an average ofcurrent values according to the calibration, and D is a dark currentvalue. Namely, the transmittance of the inspected object 8 is defined bya ratio of the output light from the inspected object 8 to the outputlight from the lamp 12 through the filter 30. In each of the numeratorand the denominator, the dark current value D is subtracted from themeasured value Si of the frequency spectrum obtained from the outputlight or from the average R of current values obtained by thecalibration. This eliminates the noise specific to the spectroscope 16.

Modifications of the present embodiment will be described below.

In the present embodiment the filter 30 was composed of the three NDfilters 26a, 26b, 26c and diffused plate 28, but the number of NDfilters may be one, two, or more than three.

The transmittances of light of the respective ND filters may also bevalues different from those of the present embodiment.

The ND filters can be replaced by filters of another type whosetransmittances of light are known.

The filter 30 can also be constructed of only a diffused plate.

The calibration driving mechanism 32 was arranged to move the filter 30in the vertical directions B so as to position the filter 30 in themiddle of the optical path from the lamp 12 to the inspected object 8,but the moving directions of the filter 30 can be arbitrary directions,e.g. horizontal directions.

The detection of the inspected object 8 was determined based onincidence of the light to the photoelectric sensor 4 providedseparately, but it may also be judged based on the quantity of theincident light to the spectroscope 16.

Whether the inspected object 8 is present or absent may also be judgedby using a weight sensor provided on the belt 3.

The projection of the light from the lamp 12 to the inspected object 8does not always have to be made from the side but can also be made fromthe top or the like, as long as the light can be projected to almost thewhole of the inspected object 8.

The light emitted from the photoelectric sensor 4 may also be light ofother wavelengths than the infrared light.

The light emitted from the lamp 12 may also be light of the otherwavelengths than the near-infrared light.

The lamp 12 may be an optical fiber and the number of lamps may also beone, two, or more than two.

The second calibration method in the present embodiment will bedescribed next with reference to FIGS. 4A, 4B, and 4C. FIGS. 4A, 4B, and4C are diagrams to show an artificial fruit or vegetable reference body(artificial fruit object) 40 as the pseudo-object member, in which FIG.4A is a perspective view, FIG. 4B a sectional view, and FIG. 4C a topplan view. This artificial fruit or vegetable reference body 40 is of arectangular parallelepiped having the height of 80 mm and the bottom 65mm square, and it is comprised of a resin vessel 46 having a glass plate44 in each of two side faces out of its side faces 42, and a lighttransmitting body (optically transparent material) 48 retained therein.The top surface of the vessel is covered by a plastic lid 50 of the samematerial as the resin vessel 46 to be closed hermetically.

The resin vessel 46 and lid 50 are made of the material obtained bymixing graphite as a filler in polyethylene (PE) and have such aproperty as to transmit light. As illustrated in FIG. 4C, the side faces42 of the vessel 46 have two types of thicknesses d1, d2, thethicknesses of the adjacent surfaces being different from each other andthe thicknesses of the opposed surfaces being identical. In the twoadjacent surfaces out of the side surfaces 42 of the resin vessel 46,the heat-resistant glass plates 44 are disposed in parallel to the sidefaces 42. These two glass plates 44 are of the same shape and are placedthrough an air layer 52 of an approximately uniform thickness withrespect to the side surfaces 42 of the resin vessel 46 without contacttherewith. At each of the upper edge and the lower edge of each sidesurface 42 of the resin vessel 46, a first flange portion 54 and asecond flange portion 56 are provided along the ridge line thereof andrecesses 54b, 56b are formed throughout the entire length in lowersurface 54a of the first flange portion and in upper surface 56a of thesecond flange portion. Each glass plate 44 is slid in the horizontaldirection to be set in the both recesses 54b, 56b, whereby the glassplate 44 is placed in the side surface 42 of the resin vessel 46.

The light transmitting body 48 is properly selected from an aqueoussolution of an acid and an aqueous solution of a sugar, depending uponthe kind of the fruits of vegetables being the inspected objects. Forexample, the aqueous solution of the acid is an aqueous solution of 1%citric acid.

The artificial fruit object 40 is equipped with a temperature measuringmember (temperature measuring means) 58 using a thermistor or the likefor measuring the temperature of the light transmitting body 48, insidethe light transmitting body 48.

Described next is a method for correcting the measured value of themeasuring device for measuring the internal quality of the fruit orvegetable using the artificial fruit object 40. FIG. 5 is a diagram toshow the structure around the measurement position 62 of the fruit orvegetable measuring device. The measuring device has the belt conveyor60 and the fruits or vegetables to be inspected (for example, oranges)placed on the belt conveyor 60 are successively fed to the measurementposition 62. At the measurement position 62 the light is projected tothe inspected object from light projecting device 70 composed of a lightsource 64, a stop 66, and a lens system 68. The light having passedthrough the inspected object is incident to a light receiving sensor 72.The light incident to the light receiving sensor 72 is separated into aplurality of wavelength band channels and spectral analysis thereof iscarried out by a known method for checking the absorbance in each of thechannels, thereby calculating the internal quality of the inspectedfruit or vegetable, for example, the acidity thereof. Since this methoditself is known, the description thereof is omitted herein.

The device is provided with the artificial fruit object 40 and theartificial fruit object 40 is arranged to be moved up and down in thedirections of arrows D in FIG. 5 at the measurement position 62 by anunrepresented mechanism so as to move between a calibration position 74located between the light projecting system and the light receivingsensor 72 and a normal position 76 where the artificial fruit object 40is retracted from the calibration position 74. The artificial fruitobject 40 is rotatable about a vertical axis 78 passing through thecenter of the bottom of the artificial fruit object 40 and one of theside faces 42 each provided with the glass plate 44 is positioned so asto be approximately perpendicular to the optical axis 80 of light 57projected from the light projecting device 70 and output light 59 fromthe artificial fruit or vegetable reference body.

FIG. 6 shows the result of the measurement where the acidities of theartificial fruit object 40 of the present embodiment and a fruit weremeasured with a lapse of time. As apparent from this figure, theacidities of the artificial fruit object 40 (values calculated fromabsorbances) measured under the same environment as in the measurementof acidities of the fruit vary with time approximately in synchronismwith those of the fruit, and it is thus seen that there is a certaincorrespondence relation between them.

Spectral absorption of the fruits or vegetables in the near-infraredregion originates in the functional groups such as O--H, C--H, and soon, and thus the measurement of the internal quality such as the acidityor the like of the fruits or vegetables by spectral analysis is carriedout based on the absorption spectra due to these functional groups. Theabsorption properties vary depending upon the environmental change ofthe temperature, the humidity, or the like. In the artificial fruitobject 40 of the present embodiment, the transmitting body is made ofthe base of the aqueous solution of the acid (citric acid). Therefore,the artificial fruit object 40 contains the same functional groups asthe fruits or vegetables and, therefore, the absorption property of theartificial fruit object 40 also varies in synchronism with the fruitsbeing the real inspected objects. This permits correction for thevariations of spectral absorption due to the environmental change.

An example of the correction method for the measurement of the internalquality of the fruit or vegetable using this reference body will bedescribed below with an example of measurement of acidity.

First obtained preliminarily is a relation of variations in measuredacidity values due to the environmental change between the artificialfruit or vegetable reference body 40 and the real fruits (which is aslope S of a straight line approximately connecting six points in FIG.7). Obtained as a reference acidity value on the other hand is ameasured acidity DR of the artificial fruit object in a state in whichthe acidities of the real fruits can be measured (calculated) without anerror (i.e., in a state (circumstance) in which correct measured valuescan be obtained). In other words, the reference acidity value DR is avalue that is so defined that when an acidity obtained in themeasurement of acidity of the artificial fruit object in a certainenvironmental state is DR, measured acidities of the real fruitsobtained in that state can be correct acidity values without correction(or with the correction value of zero). The "correct acidity values"herein mean values of acid concentrations of the real fruits obtainednot by spectral analysis but by chemical analysis.

Therefore, the value of DR is obtained using a real fruit having a knownacidity measured by chemical analysis.

The above relation of variations (the slope S of the straight line) andthe reference acidity value DR are preliminarily obtained and stored asdata in a processing system of the measuring device.

The correction operation in the actual measurement is carried out everypredetermined time, for example, every two hours. In the correctionoperation the artificial fruit object 40 of FIG. 5 is first moved downto the calibration position between the light projecting system and thelight receiving sensor 72 and the same measurement as with ordinary realfruits is carried out with the artificial fruit object 40 to calculatethe acidity thereof. Supposing the actually measured acidity is D, acorrection value C is calculated according to the following equation.

    C=(DR-D)×S

A measured value is corrected by adding the correction value obtained inthis way to a measured value of each fruit being an actually inspectedobject, so that the measured value becomes closer to a correct acidityvalue without being affected by the environmental conditions.

For example, let us suppose that the value of DR was 1.0% and the slopeS of the straight line approximately connecting the points in FIG. 7 waspreliminarily obtained as 0.9. Further, suppose the acidity of theartificial fruit object measured in the correction operation was 1.2%.In this case positive errors appear with the environmental change (i.e.,measured values are higher than actual values). In this case thecorrection value C is calculated as follows.

    C=(1.0-1.2)×0.9=-0.18

Correction is made by adding this correction value "-0.18" to a measuredvalue obtained for each fruit to be inspected (i.e., by subtracting 0.18from the measured value).

Since the environmental conditions vary with time, the correctionoperation is carried out at intervals of the predetermined time duringthe measurement period, as described above. For example, when thecorrection operation is carried out every two hours, an applicationrange of a correction value can be selected conceivably from 1) a rangein which the correction value obtained is applied to measurement datafor past two hours, 2) a range in which the correction value obtained isapplied to measurement data for next two hours, 3) a range in which thecorrection value obtained is applied to measurement data obtained forone hour each before and after the correction operation, and so on. Theway of 3) is most preferable in terms of effectiveness of thecorrection, but selection of the range does not always have to belimited to this. As the intervals of the correction operation becomeshorter and shorter, the follow-up property after the environmentalchange becomes better, so as to enhance the correction accuracy.However, the throughput of the measurement is lowered because theintended measurement is suspended during the measurement of theartificial fruit object for correction. Therefore, the intervals are setto those of an appropriate time, taking them into consideration. It canalso be contemplated that the correction operation is carried out atintervals of a shorter time for a while after on of the light source,because stability of the light source 64 is low, and then the intervalsare lengthened after the light source is stabilized.

The artificial fruit or vegetable reference body 40 of the presentembodiment is provided with the temperature measuring member 58 formeasuring the temperature of the light transmitting body 48, inside thelight transmitting body 48. This is for correction for the temperaturedifference between the artificial fruit object 40 and the fruits asactually inspected bodies. Namely, the artificial fruit object 40 ismounted on the device in many cases as in the example of the deviceillustrated in FIG. 5, whereas the fruits or vegetables such as oranges,which are objects to be measured, are supplied from predeterminedstorage. There arise no issues as long as they are in a commonenvironment. It is, however, preferable to effect temperature correctionwhen there is the temperature difference between them. Thus, theartificial fruit object 40 of the present embodiment has the temperaturemeasuring member 58 to monitor the temperature of the transmitting bodyand correction is further made with consideration to the temperaturecondition, based on the result of the monitoring, on the occasion ofobtaining the above correction value.

In the present embodiment the resin vessel 46 forming the artificialfruit object 40 can transmit the light and the transmission amountsdiffer depending upon the thicknesses thereof. In the artificial fruitobject 40 constructed as described above, the amounts of light emittedfrom the opposite vessel surface 42 when the light is projected almostnormally to the vessel side surface 42, differ depending upon thethicknesses of the side surfaces 42. Namely, when light in the samequantity is projected to two side surfaces having different thicknesses,the amount of light transmitted by the thicker side surface is smallerthan the amount of light transmitted by the thinner side surface;therefore, the thicker side surface has a lower transmittance of light.The present embodiment makes use of this property and is arranged torotate the artificial fruit object 40 according to a change in the kindor lot of inspected objects or a change of circumstances or the like,thereby changing the irradiated surface over between the surfaces havingthe different transmittances.

As described above, the present invention permits the artificial fruitobject 40 to be selected according to the change of the inspected objectwithout changing the light projecting system and light receiving system.

Since the heat-resistant glass plates 44 are provided in the sidesurfaces 42 exposed to the light projected to the artificial fruit orvegetable reference body 40 out of the side surfaces 42 of the resinvessel 46, the artificial fruit or vegetable reference body 40 hashigher durability against heat due to the projected light than in thecase without the glass plates 44.

Further, since the air layer is present between the glass plates 44 andthe side surfaces 42, it facilitates radiation of heat even when theartificial fruit or vegetable reference body 40 is heated by theprojected light, which further enhances the durability.

Since each glass plate 44 can be detached by sliding it in thehorizontal direction, the glass plate 44 can be replaced with anotherwhen the heat-resistant property of the glass plate 44 is degraded. Thiscan always assure the sufficient heat-resistant property.

It should be noted that the present embodiment is just an example andthe present invention is by no means intended to be limited to this.

Specifically, the vessel of the artificial fruit object 40 may also bemade of polyfluoroethylene (PFE), or glass like the glass plates 44,instead of polyethylene (PE).

The glass plates 44 provided in the side surfaces 42 of the resin vessel46 may be replaced by heat-resistant ND filters.

In the present embodiment the glass plates 44 are provided in the twoside surfaces out of the four side surfaces 42 of the resin vessel 46,but the number of surfaces equipped with the glass plate 44 may also beone, three, or four (all).

The opposed side surfaces 42 of the resin vessel 46 have the commonthickness, but the combination of the thicknesses of the four sidesurfaces 42 can be determined arbitrarily.

The air layer 52 between the side surfaces 42 and the glass plates 44 ofthe resin vessel 46 can be formed in an arbitrary thickness or can beexcluded.

The shape of the artificial fruit or vegetable reference body 40 doesnot always have to be the rectangular parallelepiped having the squarebottom, but may also be a polygonal prism or a circular cylinder.

The light transmitting body 48 may be of a gel substance, for example,one obtained by mixing cerium oxide of the diameter of about 0.3 μm as alight scattering body in 1% citric acid aqueous solution to disperse ituniformly and making it gel with polyacrylamide gel.

In the present embodiment the artificial fruit object 40 was arranged tobe moved up and down at the measurement position 62, but anotherconceivable configuration is such that the artificial fruit object 40 isfixed above or below the measurement position 62 and on the occasion ofcalibration the light projecting device 70 and light receiving sensor 72are moved up or down together.

The rotation of the artificial fruit object 40 can also becounterclockwise.

The artificial fruit object 40 may also be arranged to rotate about ahorizontal axis passing the center of the side surfaces 42 while beingapproximately normal to the optical axis of the projected light from thelight projecting device 70, instead of the vertical axis 78 passing thecenter of the bottom. In this case it is desirable to make thethicknesses of the side surface and the top surface or the bottomsurface different from each other and provide each surface with aheat-resistant glass plate according to the above-stated method.

The axis of rotation of the artificial fruit object 40 does not alwayshave to pass through the center of the bottom of the vessel 46 as longas it is an axis extending along the vertical direction.

On the other hand, the present invention permits the internal quality ofthe inspected objects to be measured under the same conditions,irrespective of the sizes of the inspected objects. The details will bedescribed below.

FIG. 8 is a schematic structural diagram of a device according to thepresent embodiment. The components described above will be omitted fromthe description. Each of projection optical system 70 and spectroscope72 can be moved up and down in the vertical directions indicated byarrows F and G, by a linear motor (not illustrated). During themeasurement of an inspected object 88, the optical axis 80 of theprojection optical system 70 is made coincident with the optical axis 94of receiving lens 92 of the spectroscope 72 and they are moved up anddown so as to locate the equator part 90 of the inspected object 88 onthese optical axes.

The projection optical system 70 is composed of a lamp 64, a stop 66,and a lens 68. The lamp 64 projects light 96 toward the inspected object88 and the light 96 is projected to the inspected object 88 through thestop 66 and lens 68 disposed normally to the optical axis 80 of theprojection optical system between the lamp 64 and the belt conveyor 60.The stop 66 is constructed in such structure that the size of aperture100 is continuously variable in a concentric circle shape by stop wings.The light 96 emitted from the lamp 64 passes through the aperture 100opening in a predetermined size according to the kind of the inspectedobject 88 and is properly condensed by the lens 68 to irradiate theinspected object 88 around the equator part 90. The projection opticalsystem 70 is arranged to be capable of being moved up and down alltogether. This structure permits the height of the whole apparatus to bechanged according to the size of the inspected object 88 and the equatorpart 90 of the inspected object 88 is always on an extension line of theoptical axis 94 of the receiving lens 92 of the spectroscope 72,irrespective of the size of the inspected object 88. Therefore, thelight 96 can always be projected toward the equator part 90 of theinspected object 88.

For example, when a large inspected object 88b is measured, theprojection optical system 70 and spectroscope 72 are moved up asindicated by the dashed lines. In this way, the light is alwaysprojected to the region around the equator part 90b of the inspectedobject 88b, irrespective of the size of the inspected object, so thatthe spectroscope can receive the light emerging from the region aroundthe equator part 90b.

Therefore, the internal quality of each inspected object can be measuredunder the same conditions.

The stop 66 of the projection optical system 70 will be described next.FIG. 9 is a perspective view to show the structure of the projectionoptical system 70.

In the present embodiment the stop 66 has the aperture 100 which isarranged to be continuously variable in the concentric circle shape.When the light is projected in a constant projection amount from thelamp 64 disposed behind the stop 66, the light is emitted in an amountproportional to the aperture diameter of the aperture 100 from theaperture 100 in the front surface of the stop 66.

The aperture diameter of the aperture 100 is set based on the kind ofthe fruit or vegetable being the inspected object 88. For measuring theinternal quality of the fruit or vegetable that is apt to transmit thelight relatively easily, the aperture diameter of the aperture 100 isset to be so small as to reduce the projection amount to the inspectedobject 88. On the other hand, in the case of the fruit or vegetable thatis resistant to transmission of the light, the aperture diameter of theaperture 100 is set to be so large as to increase the projection amountto the inspected object 88. When the aperture diameter is set accordingto the kind of the inspected object 88 so as to change the amount of thelight projected onto the inspected object 88 as described above, theamount of light emitted from the inspected object 88 can be controlledso as to be not less than a fixed value, irrespective of the kind of theinspected object 88, whereby the internal quality of the fruit orvegetable can be measured more accurately independent of the kind of theinspected object 88.

Examples of the measurement in the present embodiment will be describedbelow. The description of the calibration described above will beomitted herein.

A first example is the measurement of the internal quality of an orangewhich is apt to transmit the light easily. The aperture 100 of the stop66 is set to the minimum diameter. In this case, the projection amountto the inspected object 88 is small but the amount of light emitted fromthe inspected object 88 is sufficiently large. The internal quality ofthe inspected object 88 is thus measurable by an absorption spectrum ofthe emitted light.

First, the inspected object 88 is mounted on the belt conveyor 60 formeasurement. Then the projection optical system 70 and spectroscope 72are moved up and down according to the size of the inspected object 88,so as to make their optical axes 80, 94 aligned with each other andlocate the equator part 90 of the inspected object 88 on these opticalaxes 80, 94.

In this state the light is projected from the lamp 64 toward theinspected object 88. The light 96 emitted from the lamp 64 travelsthrough the aperture 100 of the stop 66 to enter the lens 68. The lightproperly condensed by the lens 68 is projected onto the region aroundthe equator part 90 of the inspected object 88. The light projected ontothe inspected object 88 is reflected and absorbed in part in the surfaceand inside of the inspected object 88 and thereafter the light isemitted to and received by the spectroscope 72.

The absorption spectrum of the light received by the spectroscope 72 ismeasured. Absorption spectra differ among the inspected objects 88 andthe internal quality of each inspected object 88 can be measured basedthereon.

A next example is the measurement of the internal quality of an applethat is resistant to transmission of the light. The maximum diameter isselected for the aperture 100 of the stop 66. In this case theprojection amount to the inspected object 88 is large and the amount oflight emitted from the inspected object 88 is thus sufficiently large.Therefore, the internal quality of the inspected object 88 is measurableby an absorption spectrum thereof.

The other measurement conditions than this are the same as in the caseof the inspected object of the orange, so that the internal quality ofthe inspected object 88 can be measured based on the absorption spectrumof the emitted light from the inspected object 88.

Modifications of the present embodiment will be described below.

The present embodiment is arranged to move the projection optical system70 and spectroscope 72 up and down in order to align the optical axis 80of the projection optical system 70, the optical axis 94 of thereceiving lens 92, and the equator part 90 of the inspected object witheach other, but another conceivable configuration is such that theposition of the belt conveyor 60 carrying the inspected objects 88 ismoved up and down. It can also be contemplated that the light projectionposition onto the inspected object 88 is varied by setting a mirror inthe projection optical system 70 and changing the angle of this mirror.In a further configuration, a mirror is provided between the receivinglens 92 of the spectroscope 72 and the inspected object 88 so that theemitted light from the equator part 90 of the inspected object 88 isalways received with changing the angle of this mirror.

The aperture 100 was arranged to be changed in the concentric circularshape in the present embodiment, but the aperture may also be of anothershape as long as it can control the amount of light passing through thestop 66. In another conceivable configuration the shape of the apertureis constant and the opening time of the aperture is controlled. Thecontrol may also be conducted using filters.

In the present invention the position of the inspected object on themoving means can be detected and the measurement can be carried out whenthe inspected object is located correctly at the measurement position.The details will be described below.

FIG. 10 and FIG. 11 are diagrams for conceptually explaining theschematic structure of a sugariness and acidity measuring device of thepresent embodiment, in which FIG. 10 is a top plan view and FIG. 11 is aside view.

In FIG. 10 the belt conveyor 60 is moving along the arrow direction J inthe figure, i.e., to the right in the figure. There are oranges m asinspected objects mounted at random on the belt conveyor 60. In FIG. 10six oranges m are placed on the conveyor 60.

A first photoelectric sensor 102, which is composed of a pair of lightprojecting element 102a and light receiving element 102b such as aphotodiode or the like, is located on either side of the conveyor and atthe upstream extremity of the belt conveyor 60. The light projectingelement 102a emits detection light toward the light receiving element102b. The light receiving element 102b receives it to convert the lightto an electric signal and outputs the electric signal to CPU 120(central processing unit: FIG. 12) described hereinafter.

Likewise, a second photoelectric sensor 103, which is composed of a pairof light projecting element 103a and light receiving element 103b suchas a photodiode or the like, is located on either side of the conveyorand at the downstream extremity of the belt conveyor. As in the case ofthe first photoelectric sensor 102, the light projecting element 103aalso emits detection light toward the light receiving element 103b inthe second photoelectric sensor 103 and the light receiving element 103breceives it to convert the light to an electric signal and outputs theelectric signal to the CPU 120.

On the upstream side in the middle part of the belt conveyor there is ameasurement system for actually performing the main measurement ofsugariness and acidity of the inspected object. The measurement systemis composed of a light source 110a for emitting light including thenear-infrared region and a spectroscope 110b for receiving light havingbeen transmitted by the inspected object m. The spectroscope 110bspectroscopically resolves the received light into a plurality offrequency components and outputs signals according to intensities of therespective component beams to the CPU 120. The details of themeasurement will be omitted from the description herein, because it isknown.

In the above structure the dimensions of each part are determinedarbitrarily according to circumstances and conditions, and in apreferred example of the present embodiment the distance between thefirst and second photoelectric sensors along the moving direction of thebelt conveyor is set to 800 mm and the center of the measurement system(the position indicated by the chain line X₀ in the figure) is set atthe position 350 mm apart from the first photoelectric sensor. Themoving speed of the belt conveyor 60 is set to approximately 300 to 1000mm/sec. It should be noted that the various numerical values describedabove are just an example and the present invention is by no meansintended to be limited to this example.

Next referring to FIG. 11, the belt conveyor 60 is wound around tworollers 111 and 112. The downstream roller 112 is connected to a powersource not illustrated and rotates in the direction of the arrow in thefigure (clockwise) to drive the belt 60. A rotational shaft 112a of thedownstream roller 112 is connected through a belt 114 to a rotationalshaft 113a of an encoder 113 disposed adjacent to the roller 112.

In this structure the encoder 113 rotates in connection with movement ofthe belt conveyor 60. The encoder 113 outputs a pulse signal accordingto an amount of the rotation and in the present embodiment the output ofthe encoder is set so as to be one pulse per moving distance 0.1 mm ofthe belt conveyor. Therefore, the moving amount of the belt conveyor 60can be monitored by counting the number of output pulses from theencoder 113.

The operation of the device of the present embodiment will be describednext. First, FIG. 12 is a block diagram to show the schematic structureof the control system in the present device. As described above, theoutputs of the first photoelectric sensor 102, the second photoelectricsensor 103, the sensor 110 for the main measurement, and the encoder 113are connected to the CPU 120 for controlling the operation of the entiredevice. The CPU 120 converts the input signals to digital signals asoccasion may demand and uses them as information for controlling theoperation of the device. In addition, an inspected object collecting andclassifying device 115 is further connected to the CPU 120. Thecollecting and classifying device 115 is a device disposed downstream ofthe belt conveyor 60 and arranged to collect the inspected objectsdischarged from the belt conveyor 60 and classify them according to thenecessity. As detailed hereinafter, the collecting and classifyingdevice classifies the inspected objects according to the measurementresult in response to instructions from the CPU 120.

The actual measurement is carried out as follows.

While the belt conveyor 60 is driven at the constant rate, the inspectedobjects m (oranges herein) are successively supplied from inspectedobject supply means not illustrated at the upstream end of the conveyor60 to be mounted at random on the belt conveyor 60. The term "at random"herein means random placement without using any particular means forpositioning, adjusting the distance between inspected objects, orproviding partitions on the conveyor.

The light emitting element 102a of the first photoelectric sensor alwaysemits the light of constant intensity toward the light receiving element102b during the measurement operation of the device. When nothingintercepts the light between the both elements, the light receivingelement 102b always receives the light of constant intensity, so thatthe output signal of the first photoelectric sensor is of a constantlevel (high level H). The inspected objects are supplied from theupstream end of the belt conveyor onto the conveyor 60 and are moved tothe downstream with the driving of the conveyor 60. When the firstinspected object reaches the position of the first photoelectric sensor,the inspected object m comes to intercept rays traveling from the lightemitting element 102a to the light receiving element 102b. While theinspected object m passes the position of the first photoelectricsensor, the light receiving element 102b receives no light, so that theoutput signal of the first photoelectric sensor is kept in a low levelL, lower than the aforementioned high level H, during a period accordingto the width of the inspected object m. In this way the output signal ofthe first photoelectric sensor becomes a signal waveform of arectangular form including the information that indicates the timeperiod in which the inspected object m passed the position of thesensor. An example of this output signal waveform of the photoelectricsensor is illustrated in FIG. 13. In FIG. 13 three low-level portionsrepresented by m₁ to m₃ indicate that three inspected objects passed theposition of the first photoelectric sensor.

As described above, the pulse signal indicating the moving amount of thebelt conveyor 60, outputted from the encoder 113, is also input into theCPU 120. With this pulse signal, the passage data of the inspectedobjects m obtained based on the above-stated output signal of the firstphotoelectric sensor can be converted to information about the sizes andpositions of the inspected objects. More specifically, for example, twoedges T₁, T₂ of a low-level portion m₃ of the signal in FIG. 13correspond to passage start and end times, respectively, when theinspected object m₃ passed the position of the first photoelectricsensor, and the lateral diameter of the inspected object m₃ can becomputed by subtraction between pulse counter numbers of the encoder atthe both times T₁, T₂. For example, supposing the pulse counter numberat T₁ is 61400 and the pulse counter number at T₂ is 62000, the numberof pulses during the passage of the inspected object m₃ at the positionof the photoelectric sensor is obtained as follows.

    62000-61400=600

Since the encoder 113 is set to generate one pulse per movement of 0.1mm (i.e., 0.1 [mm/pulse]), the lateral diameter of the inspected objectm₃ can be recognized as follows.

    600 [pulses]×0.1 [mm/pulse]=60 mm

Counting the encoder pulse number after the inspected object leaves theposition of the first photoelectric sensor, the CPU can also alwaysobtain the positional information of the inspected object.

The CPU 120 calculates the position of the center of the lateraldiameter, i.e., the position of the center of each inspected object inthe moving direction from the information about the size (lateraldiameter) of the inspected object m obtained as described above. The CPU120 further obtains the timing when the center of the inspected object mpasses the main measurement position X₀, based on the information aboutthe center position calculated and the moving amount obtained from theencoder pulse signal, and controls the measuring device to perform themeasurement of sugariness and/or acidity at the timing obtained.

This device further has the second photoelectric sensor near thedownstream extremity of the belt conveyor. The second photoelectricsensor measures the lateral diameter and position of the inspectedobject in the same manner as the first photoelectric sensor does, andcompares measured data with the data obtained by the first photoelectricsensor for the same inspected object to detect whether a positionaldeviation of the inspected object occurred midway of the movement on thebelt conveyor. Specifically, according to processing similar to that ofthe first photoelectric sensor signal, the lateral diameter informationand center position information is obtained and the lateral diameter andcenter position of the same inspected object are compared with thoseobtained from the signal of the first photoelectric sensor. If there isa deviation of either one there is no guarantee that this measurementwas carried out at the correct position. Then the CPU 120 sends an errorsignal to the collecting and classifying device 115 disposed downstreamof the belt conveyor and the collecting and classifying deviceclassifies the inspected object corresponding to the error signal as aninspected object to be measured again.

The operation of the CPU 120 in the process described above isillustrated in the flowchart of FIG. 14.

In the operation illustrated in the flowchart of FIG. 14, after thestart of the measurement, step S1 is first carried out to detect whetheran inspected object has passed the first photoelectric sensor. The CPUwaits for detection of passage here and proceeds to step S2 withdetection of passage.

Step S2 is to read the passage data (pulse data) of the inspected objectbased on the signal obtained from the first photoelectric sensor and thepulse signal from the encoder.

Then the CPU converts the passage data of the inspected object to thelateral diameter data (in units of mm) based on the pulse data in stepS3.

In step S4 the CPU next determines whether the lateral diameter iswithin a normal range. When the lateral diameter is over the normalrange, it is assumed that two or more inspected objects are placed closeto each other so as to become continuous. In that case the centerposition of each inspected object cannot be specified and themeasurement is impossible.

Therefore, the CPU proceeds to step S22 to output an error signal.

When step S4 results in determining that the lateral diameter is withinthe measurable range, the CPU goes to Step S5 to enter a process fornormal lateral diameters.

In step S6 the CPU calculates the main measurement position as aposition of the center of the lateral diameter.

In step S7 the CPU once saves the main measurement position obtained instep S6, as arrangement information of the inspected object in a waitingstate for the measurement.

In step S8 the CPU determines whether there is an unmeasured object forwhich the arrangement information in the measurement-waiting state isstored. In other words, the CPU stands by before the arrangementinformation of an inspected object in the measurement-waiting state isobtained.

When step S8 results in determining that there is an inspected object inthe measurement-waiting state, the CPU reads the arrangement informationof the inspected object in the measurement-waiting state in step S9.

In step S10 the CPU then stands by before the main measurement isfinished as to the amount of transmitted light through the inspectedobject for the measurement of sugariness and acidity.

After completion of the measurement, the CPU goes to step S11 tocalculate the sugariness and acidity based on the measurement resultobtained in step S10 and store the result in connection with thepositional data.

After that, in step S12 the CPU stands by before the inspected objecthas passed the second photoelectric sensor at the downstream end.

When the passage of the inspected object is detected in step S12, theCPU goes to step S13 to read the passage data of the inspected objectbased on the signal obtained from the second photoelectric sensor.

Then in step S14 the CPU reads the position and lateral diameter data ofthe inspected object upon the passage at the first photoelectric sensorin the sequentially next data out of the data with which the sugarinessand acidity operation is completed.

In step S15 the CPU then calculates from the position data at the secondphotoelectric sensor read in S13, position data when the inspectedobject corresponding to the data passed the first photoelectric sensor,based on the distance between the first and second photoelectricsensors. This is an operation to subtract the distance between the twosensors from the position data obtained by the second photoelectricsensor, thereby obtaining where the inspected object of interest shouldhave been located on the past occasion of the passage at the firstphotoelectric sensor.

In step S16 the CPU then compares the position (II) at the firstphotoelectric sensor, obtained from the position at the secondphotoelectric sensor in S15, with the actual position (I) at the firstphotoelectric sensor, read in S14. If the position (II) obtained in S15deviates over a predetermined amount on the upstream side with respectto the position (I) read in S14 (or if the detection timing is too late)the inspected object is considered to drop out of the conveyor in thepath from the first photoelectric sensor to the second photoelectricsensor. Therefore, the CPU regards it as abnormal and goes to step S20to delete the relevant data read in step S14. The CPU then generates anerror signal in step S21 and returns to S14 to read the next data at thefirst photoelectric sensor.

When in the position comparison in step S16 the deviation of theposition (II) to the upstream with respect to the position (I) is notmore than the predetermined amount (or when the detection timing is nottoo late), the CPU regards it as normal and goes to step S17 todetermine this time whether the position (II) deviates over apredetermined amount on the downstream side with respect to the position(I). When the deviation is over the predetermined amount on thedownstream side (or when the detection timing is too early), it isassumed that the positional deviation of the inspected object occurredon the conveyor and there is no guarantee that the main measurement wascarried out at the correct measurement position. Therefore, the CPUregards it as abnormal and goes to step S22 to generate an error signal.

When in step S17 the deviation to the downstream is not more than thepredetermined amount, the CPU regards it as normal and goes to step S18.In step S18 the CPU determines whether the lateral diameter of theinspected object obtained from the passage data at the secondphotoelectric sensor is equal to that obtained from the data at thefirst photoelectric sensor before the main measurement, which was readin S14. In the abnormal case, i.e., where they are not equal, it isconsidered that there occurred a deviation in the mount direction of theinspected object during the intermediate process (i.e., there occurred achange of the posture, for example, a change of the posture of theinspected object when the orange being the inspected object moved on theconveyor from a lying state to an upright state) or an identificationerror of the inspected object, and then the CPU proceeds to step S22 togenerate an error signal.

When the determination in step S18 is normal, the CPU goes to step S19to determine whether the measurement of sugariness and acidity for theinspected object of interest is finished. If the measurement is notfinished yet the CPU proceeds to step S22 to generate an error signal.

When step S19 results in determining that the measurement is finished,the CPU terminates the measurement process under a decision that therewas no problem in the measurement process and the correct measurementwas carried out.

Steps S21 and S22 are steps carried out when the various anomalies aredetermined in the above various determination steps. The CPU outputs anerror signal to the collecting and classifying device to direct thecollecting and classifying device to classify the measured object ofinterest into a category of inspected objects to be measured again.

The present invention was described above with reference to theembodiment, but it should be noted that the embodiment described aboveis just an example and the present invention is by no means intended tobe limited to the various elements of the embodiment and can involve avariety of modifications.

For example, the present embodiment has the inspected object supplymeans on the upstream side of the belt conveyor to automatically supplythe inspected objects, but the device may also be arranged to place eachof the inspected objects onto the conveyor by manual operation. Inpractice, where the inspected objects are fruits or vegetables easy tobruise in the event of collision, such as peaches, they are oftenmounted by hand.

The device of the present embodiment was directed to the measurement oforanges, but the present invention can also be applied to variousdevices adapted for the measurement of the other fruits or vegetables,or to devices adapted for measurement during movement of some inspectedarticles mounted on the moving means, without having to be limited tothe fruits or vegetables.

Although the device of the present embodiment is arranged to measure thesugariness and acidity, the present invention can also be applied tomeasurement of the other internal qualities of the fruits or vegetables,of course.

The second embodiment of the present invention will be described belowreferring to FIG. 15. Here, the description of the same components as inthe first embodiment will be omitted and only different portions will bedescribed herein.

The receiving lens of the spectroscope 16 is provided with a shutter 34of an opening and closing type, opening and closing of which iscontrolled by a shutter driving mechanism 36 using a solenoid. Theshutter is moved in the vertical directions K.

The control section 18 is connected to the calibration driving mechanism32 and to the shutter driving mechanism 36 and outputs signals fordriving them to control the driving of the calibration driving mechanism32 and the shutter driving mechanism 36.

The shutter driving mechanism 36 is arranged to drive the shutter 34immediately after completion of the calibration by a driving signal fromthe control section 18. The shutter 34 is moved and positioned over theentire surface of the receiving lens so as to prevent the external lightfrom entering the receiving lens of the spectroscope 16. In this statecurrent (dark current) appearing from photoelectric conversion in thecontrol section 18 is very weak. This originates in the noise etc.specific to the device and more accurate measured values can be obtainedby subtracting the value of the dark current from the above measuredvalues.

Described below is the step of measurement of the internal quality ofthe fruit or vegetable according to the present embodiment. Onlydifferent portions from the first embodiment will be described herein,too.

After completion of the measurement of the base line, the spectroscope16 outputs an end signal to the control unit 18. Receiving this signal,the control section 18 outputs a driving signal to the solenoid of theshutter driving mechanism 36. The shutter driving mechanism 36 moves theshutter 34 so as to cover the entire surface of the receiving lens ofthe spectroscope 16 in response to this driving signal, therebypreventing the external light from entering the spectroscope 16. In thisstate the spectroscope 16 measures the dark current. The dark currentresults from the noise etc. specific to the device, which is a verysmall value. The arithmetic operation unit 20 subtracts this value fromthe base line or from a measured value of each inspected object 8,whereby a more accurate measured value can be obtained for each object.

Here, the transmittance T of each inspected object 8 (the i-th objectout of the total n), used in the evaluation of the internal quality ofthe inspected objects 8, is expressed by the following equation:

    Ti=(Si-D)/(R-D)                                            (1)

where Si is a measured value of the frequency spectrum of the outputlight, after absorbed in part within the inspected object 8, R isaverage of current values by the calibration, and D is an average ofdark current values. Namely, the transmittance of the inspected object 8is defined by a ratio of the output light from the inspected object 8 tothe output light from the lamp 12 through the filter. In each of thenumerator and the denominator, the average D of dark current values issubtracted from the measured value Si of the frequency spectrum obtainedfrom the output light or from the average R of current values obtainedby the calibration. This eliminates the noise specific to thespectroscope 16.

The present embodiment is arranged to measure the dark currentimmediately after the calibration, but the calibration may also becarried out immediately after the measurement of the dark current.

The other structure, steps, and effects than above are the same as inthe first embodiment.

The third embodiment of the present invention will be describedreferring to FIG. 16 to FIG. 18. The same components as in the firstembodiment will be omitted from the description and only differentportions will be described herein.

As illustrated in FIG. 16, the device 1 of the present embodiment iscomposed of shield buckets 5, the sensor 4, the measuring section 6, andso on.

The inspected objects 8 such as melons or the like are mounted on therespective shield buckets 5 mounted on the belt conveyor 2. The beltconveyor 2 moves the inspected objects 8 in the longitudinal direction Athereof. The sensor 4 and measuring section 6 are disposed in the middleof the moving direction A of the belt conveyor 2. The sensor 4 is aphotoelectric sensor, which is arranged to project infrared light 10onto the belt conveyor 2 and measure the reflected light therefromwhereby the sensor 4 can obtain information about presence/absence,spacing, and position of the inspected object 8 on the belt conveyor 2.The measuring section 6 is located downstream of the sensor 4 in themoving direction of the belt conveyor 2 and is arranged to project lighttoward the inspected object 8 and measure the internal quality of theinspected object 8 from light outgoing from the inspected object 8.

The measuring section 6, as illustrated in FIG. 17, is composed of lamps215, first optical fibers 217, a second optical fiber 219, a filterportion 221, a first shutter 223, a second shutter 225, a spectroscope227, the optical sensor 4, a control unit 229, an arithmetic operationunit 231, and so on.

The lamps 215 are placed so as to be capable of projecting the lightfrom the side to almost the whole of the inspected object 8, three tofive lamps being located on either side of the inspected object 8. Thelight projected from the lamps 215 toward the inspected object 8 is onehaving wavelengths, for example, in the near-infrared region (650 to 950nm). After this light is absorbed in part inside the inspected object 8receiving the projected light, transmitted light is emitted from theinspected object 8.

The first optical fibers 217 in the number equal to the number of lamps215 are provided between the lamps 215 and the inspected object 8. Alight receiving portion of each optical fiber 217 is directed toward theassociated lamp 215, so as to be capable of directly receiving the lightfrom the lamp 215.

The first shutter 223 and filter portion 221 are disposed in the middleof the optical paths of the first optical fibers 217. The filter portion221 is, as the filter 30 shown in FIG. 3, composed of ND filters and adiffused plate. The first shutter 223 is arranged to be opened or closedby the solenoid, based on whether the inspected object 8 is present orabsent in the measuring section 6. While the first shutter 223 is in anopen state, the light from the first optical fibers 217 is incident tothe filter portion 221. Since the structure and effect of the filterportion 221 are similar to those of the filter 30 of the firstembodiment, the description thereof is omitted herein.

The second optical fiber 219 having the second shutter 225 is connectedto an aperture portion 240 in the bottom part of the shield basket 5.The second shutter 225 is opened and closed by the solenoid (notillustrated), based on whether the inspected object 8 is present orabsent in the measuring section 6. While the second shutter 225 is in anopen state, the light having been transmitted by the inspected object 8travels through the aperture portion 240 in the bottom part of theshield basket 5 to enter the second optical fiber 219.

The first and second optical fibers 217, 219 join to form the thirdoptical fiber 233 to be connected to the spectroscope 227, so that thespectroscope 227 can receive the light from the lamps 215 through thefilter portion 221 of the first optical fibers 217 or the transmittedlight from the inspected object 8 through the second optical fiber 219.The spectroscope 227 can measure an absorption spectrum of the lightreceived or the amount of the light. This permits the measurement of theinternal quality such as the sugariness or the like of the inspectedobject 8.

The sensor 4 described above is connected to the control unit 229 andthe control unit 229 converts the quantity of the light incident to theoptical sensor 4 to current by photoelectric conversion and candetermine whether the inspected object 8 is present or absent in themeasuring section 6, based on whether the current is larger than apredetermined value. Therefore, the control unit 229 can detect thespacing between the inspected objects 8 on the conveyor 2, based on thedetermination. The above predetermined value is a value determinedaccording to the kind, the size, measuring speed, etc. of the inspectedobjects 8, which is set by the user of the device before the start ofthe measurement or during the measurement.

Further, the control unit 229 is connected to the first shutter 223 andto the second shutter 225 and outputs signals for driving them. When thespacing between the inspected objects 8 is less than the predeterminedvalue, the second shutter 225 is opened while the first shutter 223 isplaced so as to interrupt incidence of light to the filter portion 221.In this case the spectroscope 227 receives the light from the shieldbasket 5 through the second optical fiber 219 but does not receive thelight from the first optical fibers 217. In contrast with it, where thespacing between the inspected objects 8 is not less than thepredetermined value, the first shutter 223 is opened while the secondshutter 225 is placed so as to interrupt incidence of the light to thesecond optical fiber 219. In this case the spectroscope 227 does notreceive the light from the second optical fiber 219 but receives thelight from the lamps 215 through the filter portion 221. The calibrationof the spectroscope 227 is carried out in this state, based on the lightfrom the filter portion 221. Namely, the calibration of the device canbe carried out on arbitrary occasions, not only at the start of themeasurement but also during the measurement, with the light travelingthrough the filter 221, so that the internal quality of the fruits orvegetables can be measured more accurately without being affected by thevariations of the base line due to the measurement.

The arithmetic operation section 231 is connected to the spectroscope227 and receives an input of current of a frequency spectrum based onthe transmitted light from the inspected object 8 or current in thecalibration. The arithmetic operation section 231 can measure theinternal quality of the inspected object 8 without influence of thevariations of the base line, the noise of the spectroscope 227, etc.,based on these current values.

With the device in the above structure, where the inspected objects 8arranged in the longitudinal direction of the belt conveyor 2 aremeasured, the spacing between the inspected objects 8 can be detected,and the calibration of the device and the measurement of the darkcurrent can be performed every time a portion where the spacing betweenthe inspected objects 8 is not less than the predetermined value reachesthe measuring section 6. Therefore, the calibration can be carried outon desired occasions, not only before the start of the measurement butalso even after the start of the measurement, so that the measurementdoes not have to be suspended for the calibration. Hence, the internalquality of the fruits or vegetables can be measured accurately bycarrying out the calibration of the device for each of the inspectedobjects 8 without interruption of the measurement.

Described below is the step of the measurement of the internal qualityof the fruits or vegetables according to the present embodiment.

First, the calibration of the device and the measurement of the darkcurrent are carried out prior to the start of the measurement. Thecalibration is carried out in such a manner that with the second shutter225 being in the closed state, the first shutter 223 is opened to permitthe spectroscope 227 to measure the quantity of the light projectedthereto from the first optical fibers 217 through the filter portion221. The quantity of this light is converted to a current value in thespectroscope 227 and this is used as a base line (or a reference value)of the measurement of the inspected objects 8. On the other hand, themeasurement of the dark current is carried out in a state in which boththe first and second shutters 223, 225 are closed so as to prevent theexternal light from entering the spectroscope 227. The dark current iscurrent that the spectroscope 227 itself has in the shield state of thespectroscope 227 and current values without influence of thespectroscope 227 itself can be calculated by subtracting the darkcurrent value from measured values thereafter (current values afterphotoelectric conversion) by the spectroscope 227.

The measurement of the internal quality of the inspected objects 8 iscarried out when each of the inspected objects 8 placed along thelongitudinal direction of the belt conveyor 2 reaches the measuringsection 6 with movement of the conveyor 2. Namely, when an inspectedobject 8 mounted on the shield basket 5 reaches the measuring section 6,the inspected object 8 is irradiated directly with the light from thelamps 215 and the emergent light, after absorbed in part inside theinspected object 8, is incident to the spectroscope 227 through theaperture portion 240 provided in the lower part of the shield basket 5and through the second optical fiber 219. The internal quality of theinspected object 8 can be measured based on a frequency spectrum of thislight. This is based on the fact that the profile of the frequencyspectrum differs depending upon the components in the inspected object8, because there exist frequencies at which the quantity of light ishigh because of the components.

The base line varies with continuation of the measurement. This iscaused by the environmental change of the temperature or the like of thespectroscope 227, the measuring section 6, or the region around them.The influence due to fluctuations of the base line has to be eliminatedin order to obtain correct measured values. In the present embodimentthe base line is measured at a position where the spacing between theinspected objects 8 is not less than a predetermined value. This valueis stored in the arithmetic operation section 231 connected to thespectroscope 227.

After completion of the calibration and the measurement of the darkcurrent prior to the start of the measurement, the first shutter 223 isclosed while the second shutter 225 is opened, whereby the light fromthe lamps 215 travels through the aperture portion of the shield basket5 and through the second optical fiber 219 to enter the spectroscope227. When an inspected object 8 moving on the belt reaches the measuringsection 6 in this state, the near-infrared light emitted from the lamps215 is projected onto the inspected object 8. The light is absorbed inpart by the inspected object 8 and is then emergent from the inspectedobject 8 to enter the spectroscope 227 through the second optical fiber219. Then the spectroscope 227 measures the internal quality of thisinspected object 8.

The internal quality of the inspected objects is measured successivelyevery time the inspected object 8 reaches the measuring section 6 inthis way. When during this measurement the photoelectric sensor 4detects that the spacing between the inspected objects 8 is not lessthan the predetermined value, the control section 229 determines thatthe inspected object 8 is absent in the measuring section 6 and outputsa signal for closing the second shutter 225. In response to this signalthe solenoid (not illustrated) of the second shutter 225 is driven, sothat the optical path from the shield basket 5 to the spectroscope 227is interrupted. The control section 229 also outputs a driving signal tothe solenoid (not illustrated) of the first shutter 223. In response tothis driving signal the first shutter 223 opens the optical paths of thefirst optical fibers 217 having been kept in the interrupted state,whereby the light becomes incident to the spectroscope 227 through thefilter portion 221.

The base line of the device can be measured by measuring the quantity ofthe attenuated light by this filter portion 221. Fluctuations of thebase line can be followed up as occasion may demand. The measured valueof the base line is stored in the arithmetic operation section 231.

Here, the transmittance discussed below is used for the evaluation ofthe internal quality of the inspected objects 8. Specifically, thetransmittance T of each inspected object 8 (the i-th object out of thetotal n) is expressed by the following equation:

    Ti=(Si-D)/(R-D)                                            (1)

where Si is a measured value of the frequency spectrum from the outputlight, after absorbed in part within the inspected object 8, R is anaverage of current values by the calibration, and D is the dark currentvalue. Namely, the transmittance of the inspected object 8 is defined bya ratio of the output light from the inspected object 8 to the outputlight from the lamps 215 through the filter portion 221. In each of thenumerator and the denominator, the dark current value D is subtractedfrom the measured value Si of the frequency spectrum obtained from theoutput light or from the average R of current values obtained by thecalibration. This eliminates the noise specific to the spectroscope 227.

Modifications of the present embodiment will be described below.

The first shutter 223 may also be disposed in the middle or at the endof the optical paths of the first optical fibers 217.

The second shutter 225 may also be disposed in the middle or at the endof the optical path of the second optical fiber 219. When the secondshutter 225 is disposed at the end on the belt conveyor 2 side, it ispreferably set in contact with the belt conveyor 2; it is, however,noted that the second shutter 225 does not always have to be in contactwith the belt conveyor 2.

The detection of the inspected object 8 was made by incidence of thelight to the photoelectric sensor 4 provided separately, but thedetermination may also be made according to the amount of the incidentlight to the second optical fiber 219.

The present embodiment was arranged to mount the inspected objects 8 onthe respective shield buckets 5 on the belt conveyor 2 and measure theoutput light from the bottom part of the shield buckets 5, but the beltof the conveyor may be replaced by a mesh belt that permits the lightemerging from the inspected object 8 to be measured from the bottomthereof.

The projection of the light from the lamps 215 to the inspected object 8can not be effected only from the side, but can also be effected fromthe top surface or the like as long as the light can be projected toalmost the whole of the inspected object 8.

The light emitted from the photoelectric sensor 4 may also be one of theother wavelengths than the infrared light.

The light emitted from the lamps 215 may also be one of the otherwavelengths than the near-infrared light.

The lamps 215 may also be replaced by optical fibers and the numberthereof does not have to be limited to three, but may also be one, two,or more than three.

The fourth embodiment will be described next. Here, the same componentsas in the third embodiment are omitted from the description and onlydifferent portions will be described.

In the present embodiment the calibration can be carried out onarbitrary occasions. Namely, the calibration can be carried out,irrespective of whether the inspected object 8 is present or absent inthe measuring section 6, as the user of this device desires or asoccasion may demand.

Described below is the step of the measurement of the internal qualityof the fruits or vegetables according to the present embodiment. Onlydifferent portions from the third embodiment will be described herein,too.

In the present embodiment, after the start of the measurement of theinternal quality of the fruits or vegetables, when the user of thisdevice gives instructions of the calibration start by a mechanical orelectrical operation or when the arithmetic operation section 231 or thecontrol section 229 determines that the base line of the measurement isoff a certain range, the calibration is carried out automatically,irrespective of whether the inspected object 8 is present or absent inthe measuring section 6, by closing the second shutter 225 and openingthe first shutter 223.

This permits the calibration to be carried out at an arbitrary time and,therefore, the internal quality of the fruits or vegetables can bemeasured more accurately while the base line is kept constant.

The other structure, steps, and effects than above are the same as inthe third embodiment.

The fifth embodiment will be described next. Here, the same componentsas in the third embodiment will be omitted from the description and onlydifferent portions will be described.

The present embodiment is arranged to carry out the measurement of darkcurrent, following the calibration after the start of the measurement ofthe internal quality of the fruits or vegetables.

Described below is the step of the measurement of the internal qualityof the fruits or vegetables according to the present embodiment. Here,only different portions from the third embodiment will be described,too.

After completion of the measurement of the base line, the first shutter223 is closed while the second shutter 225 is in the closed state. Thisopening and closing of the shutters is controlled by signals from thecontrol section 229. In this state the spectroscope 227 measures thedark current. The dark current is current appearing due to the noiseetc. specific to the device, which is very small. The arithmeticoperation unit 231 subtracts this value from, a measured value of thebase line or each inspected object 8, whereby a more accurate measuredvalue can be obtained for each of them.

Here, the transmittance T of each inspected object 8 (the i-th objectout of the total n), used in the evaluation of the internal quality ofthe inspected objects 8, is expressed by the following equation:

    Ti=(Si-D)/(R-D)                                            (1)

where Si is a measured value of the frequency spectrum from the outputlight, after absorbed in part within the inspected object 8, R is anaverage of current values by the calibration, and D is an average ofdark current values. Namely, the transmittance of the inspected object 8is defined by a ratio of the output light from the inspected object 8 tothe output light from the lamps 215 through the filter 221. In each ofthe numerator and the denominator, the average D of dark current valuesis subtracted from the measured value Si of the frequency spectrumobtained from the output light or from the average R of current valuesobtained by the calibration. This eliminates the noise specific to thespectroscope 227.

The present embodiment is arranged to measure the dark currentimmediately after the calibration, but the calibration may also becarried out immediately after the measurement of the dark current.

The other structure, steps, and effects than above are the same as inthe third embodiment.

The sixth embodiments of the present invention will be described belowwith reference to FIG. 18 to FIGS. 27A and 27B. The same components asin the first embodiment will be omitted from the description and onlydifferent portions will be described herein.

FIG. 18 and FIG. 19 are diagrams to illustrate a device for evaluatingthe internal quality of fruits or vegetables according to the sixthembodiment of the present invention, wherein FIG. 18 is a top plan viewthereof and FIG. 19 is a view along 19--19 of FIG. 18.

The device of the present embodiment has the belt conveyor 2 and aplurality of fruits or vegetables 8 to be inspected are mounted atrandom thereon. The belt conveyor 2 is driven in the arrow direction Pin the figure through a driving shaft not illustrated, and with thedriving of the belt conveyor 2 the fruits or vegetables 8 thereon alsomove along the predetermined conveyance path. The belt conveyor 2 isequipped with an encoder (not illustrated in FIG. 18) to monitor movingamounts of the conveyor in units of 0.1 mm.

Halogen lamp light sources 12 for projecting light toward the inspectedfruit or vegetable 8 are disposed on either side of the belt conveyor 2and at predetermined positions in the conveyance path of the beltconveyor 2. The light sources 12 are arranged to project spot lighthaving the diameter of about 2 cm toward the fruit or vegetable.

A light receiving sensor 303 for receiving light from the inspectedfruit or vegetable 8 is provided at the same position as the lightsources 12 in the conveyance path and immediately above the beltconveyor 2, as illustrated in FIG. 19. The light received by the lightreceiving sensor is stereoscopically separated into a plurality ofwavelength band channels and spectral analysis thereof is carried out bya known method for checking the absorbance in each channel, therebymeasuring and evaluating various internal qualities such as thesugariness, acidity, grade of maturity, and the like of the inspectedfruits or vegetables 8. Since this method itself is known, thedescription thereof is omitted herein.

The light sources 12, the light receiving sensor 303, and part of theconveyor 2 around them are enclosed together in a box not illustrated tobe shielded from the external light.

A position sensor 4, which is composed of a pair of light projectingelement 4a and light receiving element 4b, is disposed at an upstreamposition of the belt conveyor 2. The position of a fruit or vegetable 8on the belt conveyor can be detected from a change of an output signalfrom the light receiving element occurring when the inspected fruit orvegetable 8 intercepts the light during passage thereof between thelight projecting element and the light receiving element. Based on theposition information detected herein and moving amount informationobtained from the encoder provided in connection with the belt conveyor2, the measurement timing is controlled so as to carry out themeasurement at the moment when the inspected fruit or vegetable 8 passesthe position of the measurement by the light sources 12 and lightreceiving sensor 303.

The lateral diameter of the inspected fruit or vegetable 8 can becalculated from the moving amount information obtained from the encoderand the time period of interception of the light at the position sensor4. This means that the position sensor 4a, 4b can also be used as alateral diameter sensor.

In the above structure, the position sensor, the encoder of the beltconveyor, and the light receiving sensor all are connected to the CPU ofthe device and this CPU carries out the control of the above measurementtiming and all the controls of the device including the calculation ofthe lateral diameter and so on.

The seventh embodiment of the present invention will be described next.The present embodiment is provided with shield plates for interceptingthe stray light including the light incident from the light sources 12directly to the light receiving sensor 303, light reflected by thesurface of the inspected fruit or vegetable, light resulting fromreflection of the aforementioned reflected light from some elements ofthe device, and so on. Since the overall structure of the device issimilar to that of the sixth embodiment illustrated in FIG. 18, thedescription thereof is omitted herein and only the part of the shieldplates will be described below.

FIGS. 20A, 20B, and 20C are diagrams to show the structure near themeasurement position of the device of the seventh embodiment, whereinFIG. 20A is a side view corresponding to FIG. 19 of the sixthembodiment, FIG. 20B is a top plan view of the relevant part, and FIG.20C is a side view from a direction perpendicular to FIG. 20A.

As illustrated in FIG. 20A and FIG. 20B, the present embodiment isprovided with two shield plates 310 disposed on either side of the fruitor vegetable so as to shield the light receiving sensor 303 from thestray light including the light reflected by the surface of the fruit orvegetable 8, the light resulting from reflection of the reflected lightfrom the elements of the device, the light directly traveling from thelight sources 12 thereto, and so on. As best shown in FIG. 20C, theshield plates are set approximately horizontally at the position higherthan irradiation spots Q where the light from the light sources 12irradiates the fruit or vegetable 8 and lower than the height of thefruit or vegetable 8.

The separation between the two shield plates 310 can be selected fromthe following configurations: 1) the separation is set to a fixed lengthgreater than an expected maximum of the lateral diameter of the fruitsor vegetables as inspected objects, 2) the separation is made variableevery kind of objects with consideration to an expected maximum of thelateral diameter of the fruits or vegetables of each kind to be measured(i.e., every change of measured objects, for example, between apples andpeaches), or 3) the separation is made automatically variable accordingto the lateral diameter of each of the inspected objects.

A block diagram of a control system of the device in the case of 3) isillustrated in FIG. 21. The CPU 320 calculates the lateral diameter ofan inspected object, based on an output from the position and lateraldiameter sensor 4, and sends a command to a shield plate driving device306 so as to realize the separation between the shield plates accordingto the lateral diameter thus calculated. In response thereto the shieldplate driving device 306 drives the shield plates 310 by motor power toset the separation between the shield plates according to the command.Preferably, in order to enhance effectiveness of shield, the separationis set so as to make small the clearance between the shield plates andthe inspected fruit or vegetable.

The eighth embodiment of the present invention will be described next.The device of the eighth embodiment is also provided with the shieldplates for intercepting the stray light in the similar fashion to theseventh embodiment, but the device of the eighth embodiment is differentfrom the device of the seventh embodiment in the setting position of theshield plates. Since the overall structure of the device in the presentembodiment is also similar to that of the sixth embodiment, only thepart of the shield plates will be described below.

FIG. 22A and FIG. 22B are diagrams to show the structure near themeasurement position of the device of the eighth embodiment, whereinFIG. 22A is a side view corresponding to FIG. 19 of the sixth embodimentand FIG. 22B is a top plan view of the relevant part.

As illustrated in FIGS. 22A and 22B, the device of the presentembodiment is provided with two shield plates 311 above the inspectedfruit or vegetable 8 so as to shield the light receiving sensor 303 fromthe stray light including the light reflected by the surface of thefruit or vegetable 8, the light coming directly from the light sources12, and so on.

The height of the two shield plates 311 can be selected from thefollowing configurations: 1) the height is set to a fixed length greaterthan an expected maximum of the height of the fruits or vegetables asinspected objects, 2) the height is made variable every kind of objectswith consideration to an expected maximum of the height of fruits orvegetables of each kind to be measured (i.e., every change of measuredobjects, for example, between apples and peaches), or 3) the height ismade automatically variable according to the height of each of theinspected objects.

A block diagram of a control system of the device in the case of 3) isillustrated in FIG. 23. The CPU 320 calculates the height of theinspected object, based on an output from a height sensor 307, and sendsa command for setting the height of the shield plates according to thecalculated height to the shield plate driving device 306. In responsethereto the shield plate driving device 306 drives the motor for drivingthe shield plates 311 to set the height of the shield plates 311 so asto be a little higher than the calculated height of the inspectedobject.

FIG. 24 shows the structure of the height sensor. The height sensor isdisposed on the upstream side of the inspected object conveyance path ofthe belt conveyor 2. The height sensor is composed of light projectingdevice 307a and light receiving device 307b opposed to each other oneither side of the belt conveyor 2. The light projecting device 307a ofthe height sensor 307 has a plurality of light projecting elements 307a1aligned at equal intervals in the vertical direction and the lightreceiving device 307b has light receiving elements 307b1 aligned each atrespective heights matched with those of the corresponding lightprojecting elements 307a1 of the light projecting device 307a andarranged to receive light beams from the corresponding light projectingelements 307a1. The inspected fruit or object 8, passing between thelight projecting device 307a and the light receiving device 307b,intercepts the beams from the light projecting elements 307a1 to thelight receiving elements 307b1 located below the height of the fruit orvegetable. Namely, the height of the inspected fruit or vegetable 8 canbe detected discretely by detecting up to which height the beams areintercepted.

The ninth embodiment of the present invention will be described next.The device of the ninth embodiment is different from the seventh andeighth embodiments described above in the structure of the shieldplates.

FIG. 25 is a side view to show the structure of the shield plates in thedevice of the ninth embodiment. Each of the shield plates 312 issupported so as to be pivotable about an axis O. The structure of thecontrol system in the device of the present embodiment is similar tothat of the eighth embodiment illustrated in FIG. 23. In the device ofthe present embodiment the angular position about the axis O of theshield plates 312 is adjusted based on information about either thelateral diameter of the inspected fruit or vegetable detected by theposition and lateral diameter sensor 4 or the height of the inspectedfruit or vegetable detected by the height sensor 307 or about the both,so as to set the clearance between the shield plates and the fruit orvegetable small. FIG. 25 shows the position of the shield plates for alarge inspected object 8 illustrated by solid lines and the position ofthe shield plates for an inspected object 8' a size smaller, illustratedby dashed lines, than the large inspected object 8. The control systemof the present embodiment can be constructed in the similar structure tothat of the eighth embodiment illustrated in FIG. 23 and describedabove.

A modification of the ninth embodiment can also be constructed in suchstructure that the fruit or vegetable itself moving on the conveyorpushes the shield plates up, instead of the automatic adjustment of theposition of the shield plates. An example of this structure isillustrated in FIG. 26. In this example, an upward curl (curve) C₀ isformed at each of corners opposed on the upstream side of the shieldplates 312 and the shield plates 312 are arranged to be pushed up by theinspected object itself with the movement of the inspected object by theconveyor. In the case of this modification, the structure becomessimpler, because it obviates the need for the mechanism for detectingthe size of the inspected object and the mechanism for adjusting theposition of the shield plates in conjunction therewith.

The tenth embodiment of the present invention will be described next.The device of the tenth embodiment is characterized in that the straylight is intercepted by a tray fixed on the belt conveyor. Since theoverall structure of the device of the tenth embodiment is similar tothat of the sixth embodiment, the description thereof is omitted hereinand only the part associated with the tray will be described below.

FIG. 27A and FIG. 27B are diagrams to show the schematic structure ofthe tray in the device of the tenth embodiment. FIG. 27A is a side viewof the tray part in which the tray itself is illustrated in crosssection. FIG. 27B is a side view from a direction perpendicular to FIG.27A. As illustrated in the figures, the tray 314 is placed on the beltconveyor 2 and the inspected fruit or vegetable 8 is mounted on the tray314 in the device of the present embodiment. A hole 314a is bored ineach of side surfaces opposed in the transverse direction of theconveyor belt in the tray 314. As seen from FIG. 27A, the light from thelight sources 12 travels through the holes 314a to irradiate theinspected fruit or vegetable 8. Since the light reflected by the surfaceof the fruit or vegetable is effectively intercepted by the tray 314, itis rarely incident to the light receiving element 303. There are aplurality of trays 314 placed on the belt conveyor.

The embodiments of the present invention were described above and itshould be noted that the present invention is by no means intended to belimited to the details of these embodiments. For example, theembodiments employed the belt conveyor, but the conveying system canalso be selected from a variety of other conveying devices.

The sixth to the tenth embodiments used the two light sources disposedon either side of the conveyance path, but the number of light sourcesmay also be one or more than two. In the seventh to ninth embodiments,if the light source is provided on only one side of the belt conveyor,the shield plate on the other side can be omitted.

In the sixth to the tenth embodiments the light from the light sourcesis projected in the horizontal direction, but the light may also beprojected in an inclined state diagonally from above or below. Theembodiments are arranged to project the light in the directionperpendicular to the conveying direction by the belt conveyor, when seenfrom above, but it can also be projected in an inclined state.

Further, the halogen lamps were used as the light sources in the devicesof the embodiments, but, without having to be limited to this, the lightsources can also be selected from the other light sources that can emitthe light in the wavelength region used in the measurement.

There are no restrictions on the kind and size of the fruits orvegetables as measured objects in the devices of the present inventionand the present invention can also be applied to a variety of fruits orvegetables by properly arranging the size of the device and the numberand light quantity of the light sources.

The internal qualities measured by the devices of the present inventioninclude not only the typical examples of sugariness and acidity but alsoall other internal qualities of fruits or vegetables that can bemeasured by spectral analysis.

The eleventh embodiment of the present invention will be described next.Here, the same components as in the first embodiment will be omittedfrom the description herein and different portions will be describedmainly.

FIG. 28A and FIG. 28B are diagrams to show an artificial fruit orvegetable reference body 410 as an embodiment of the present invention,wherein FIG. 28A is a perspective view and FIG. 28B is a sectional view.This artificial fruit object is composed of a cylindrical glass vessel401 having the diameter of 65 mm and the height of 80 mm and a lighttransmitting body 402 retained therein. The top surface of the vessel isalso covered by a glass lid 404 to be closed hermetically. The lighttransmitting body is a material obtained by mixing cerium oxide havingthe size of 0.3 μm as a light scattering body in 1% citric acid aqueoussolution to make it uniformly dispersed and making it gel withpolyacrylamide gel. An amount of cerium oxide mixed is properly setaccording to the kind of the fruits or vegetables as inspected objects.

The artificial fruit object 410 of the present embodiment is equippedwith a temperature measuring member (temperature measuring means) 403using a thermistor or the like for measuring the temperature of thelight transmitting body, inside the light transmitting body 402.

Described next is a method for correcting measured values of themeasuring device for measuring the internal quality of the fruits orvegetables using the artificial fruit object 410. FIG. 29 is a diagramto show the structure around the measurement position of the fruit orvegetable measuring device. The measuring device has the belt conveyor422 and the fruits or vegetables to be inspected (for example, oranges)placed on the belt conveyor 422 are successively fed to the measurementposition. At the measurement position the light is projected to theinspected object from the light projecting device 420 composed of alight source 411, a stop 412, and a lens system 413. The light havingpassed through the inspected object is incident to a light receivingsensor 414. The light incident to the light receiving sensor isseparated into a plurality of wavelength band channels and the spectralanalysis thereof is carried out by a known method for checking theabsorbance in each of the channels, thereby calculating the internalquality of the inspected fruit or vegetable, for example, the aciditythereof. Since this method itself is known, the description thereof isomitted herein.

The device is provided with the artificial fruit object 410 and theartificial fruit object 410 is arranged to be moved up and down at themeasurement position by an unrepresented mechanism so as to be movedbetween a calibration position located between the light projectingsystem and the light receiving sensor and a normal position where theartificial fruit object 410 is retracted from the calibration position.

FIG. 31 shows the result of the measurement of the transmitted lightspectrum of the artificial fruit object in the present embodiment. Thesame figure also shows the transmitted light spectra of real fruits, amandarin orange, a pear, and an apple together with that of theartificial fruit object and it is seen from the figure that,particularly in the near-infrared region of the wavelengths above 810nm, the spectral property of the artificial fruit object 410 follows thespectral properties of the real fruits well.

In the correction method and device for the measurement of the internalquality of the fruits or vegetables described above, the measured valuesof the fruits or vegetables are corrected with the correction valueobtained using the single artificial fruit or vegetable reference body,whereas the following example illustrates a method and device forcorrection by use of a plurality of artificial fruit or vegetablereference bodies.

An example of the device for performing the calibration with a pluralityof artificial fruit objects is illustrated in FIG. 30. The deviceillustrated in FIG. 30 has a light projecting system 420 comprised of ahalogen lamp light source 411, a stop 412, and a lens system 413, and alight receiving sensor 414, similar to the device of FIG. 29. Thisdevice further has a revolver 430 in which four holes are bored.Artificial fruit objects 410a, 410b, and 410c are fit in three holes outof the four holes of the revolver. Nothing is set in one rest hole. Thethree artificial fruit objects are made based on three types ofsolutions having different concentrations. Specifically, the solutionsare citric acid solutions having the respective concentrations of 1%,2%, and 3%. The three artificial fruit objects are made all in the equalfashion to each other except for the concentrations of citric acid. Therevolver is driven by stepping motor 415 to set each of the artificialfruit objects in order at the measurement position during the correctionoperation, and the amount of transmitted light through each object ismeasured. During the normal measurement of the fruits or vegetablesexcept for the period of the correction operation, the light from thelight projecting system is projected through the through hole 431 to theinspected fruit or vegetable S.

In the device of the embodiment illustrated in FIG. 29 and describedabove the correction is carried out using the single artificial fruitobject. Accordingly, the constant correction value is presented,irrespective of the acid concentrations, in the measurement of all theinspected fruits or vegetables. In contrast with it, the measurement iscarried out with the reference bodies having the three differentconcentrations of citric acid in the device of the present embodiment.This is for carrying out the correction with higher accuracy withconsideration to the concentrations of the inspected objects, becausevariations in the measured values of acidity due to the environmentalchange of the temperature or the like possibly differ according to theacid concentrations of the inspected objects.

In this embodiment correction values are obtained using the respectiveartificial fruit or vegetable reference bodies having the citric acidconcentrations of 1%, 2%, and 3%, respectively, and the correction canbe carried out according to the acid concentrations of the inspectedobjects, using these correction values. Therefore, the correctionaccuracy is enhanced more. Specifically, the correction is implementedby obtaining a concentration-correction value straight lineapproximately linearly connecting the correction values and carrying outthe correction according to a concentration of each inspected object,based on the straight line.

The structure of the artificial fruit objects arranged in the revolvertype in this device illustrated in FIG. 30 had never been able to berealized until the structure of the small (i.e., small in the length inthe light transmission direction) artificial fruit objects wassubstantiated while adjusting the optical transmittances by use of thelight scattering body as in the present invention.

The present invention was described above based on the embodimentsthereof, but it should be noted that the present invention is by nomeans intended to be limited to the details of the embodiments.

For example, in either of the above embodiments the artificial fruitobjects were mainly made of the aqueous solution of citric acid, but,without having to be limited to citric acid, the artificial fruitobjects may also be made of a material selected from other acids andsugars or other aqueous solutions.

In the artificial fruit objects, the light diffusing body is mixed inthe aqueous solution in order to attenuate the transmitted light. It canalso be contemplated to adjust the transmittance by lowering thetransmittance of the vessel instead of the addition of the lightdiffusing body.

The vessel of the artificial fruit objects was glass in the aboveexamples, but the vessel may also be made of an optically transparentmaterial among resins. The other structure, operation, and effects thanabove are the same as in the first embodiment.

The twelfth embodiment of the present invention will be described next.Here, the same components as in the first embodiment will be omittedfrom the description and different portions will be described mainly.

FIG. 32A and FIG. 32B are diagrams to show an artificial fruit orvegetable reference body (artificial fruit object) 540 of the presentembodiment, wherein FIG. 32A is a perspective view and FIG. 32B is asectional view. The present embodiment employs the artificial fruitobject 540 in place of the artificial fruit object 40 of the firstembodiment. This artificial fruit or vegetable reference body 540 iscomposed of a resin vessel 546 shaped in a rectangular parallelepipedhaving the height of 80 mm and the bottom 65 mm square and having aglass plate 544 in one surface out of its side surfaces 542, and a lighttransmitting body 548 retained therein. The top surface of the vessel iscovered by a plastic lid 550 of the same material as the resin vessel546, to be closed hermetically. At the side surface 542 of the resinvessel 546, the heat-resistant glass plate 544 is disposed in parallelto the side surface 542.

In the present embodiment, as illustrated in FIG. 32B, an inside surface500 of the vessel 546 is inclined with respect to the verticaldirection. This structure makes the distance between the side surfaces542 narrower and narrower from top to bottom of the vessel 546 whilethicknesses of the side surfaces 542 become larger from top to bottom ofthe vessel 546. When the light is projected from the direction Q andemitted in the direction R, the light projected to the upper part of theresin vessel 546 travels through thin portions of the side surfaces 542and through a longer portion of the light transmitting body 548 to theoutside, whereas the light projected to the lower part of the resinvessel 546 travels through thick portions of the side surfaces 542 andthrough a shorter portion of the light transmitting body 548 to theoutside. This means that the light projected to the upper part of theresin vessel 546 is less affected by the side surfaces 542 than thelight projected to the lower part and is thus transmitted at highertransmittances.

Described below is a method for correcting measured values by theinternal quality measuring device of fruits or vegetables using thisartificial fruit object 540. In the present embodiment the artificialfruit object 540 is arranged to be capable of being moved finely up anddown within a range in which the light can be projected to either partof the side surface 542 of the resin vessel 546 at the calibrationposition 74 of FIG. 5.

In the present embodiment the resin vessel 546 forming the artificialfruit object 540 can transmit the light and varies transmission amountsof the light, depending upon its thicknesses. With the artificial fruitobject 540 constructed as described, when the light is projectedapproximately normally to the side surface 542 of the vessel, amounts ofemergent light from the opposite side surface 542 of the vessel differdepending upon the thicknesses of the side surfaces 542. Namely, whenthe light is projected in the same quantity to two portions havingdifferent thicknesses in the side surface 542, the amount of thetransmitted light through the thicker portion is smaller than the amountof the transmitted light through the thinner portion, so that thethicker portion has a lower transmittance of light. The presentembodiment, making use of this property, can change the projectedportion in the side surface 542 among portions having differenttransmittances by moving the artificial fruit object 540 up and down,according to the kind of the inspected objects, a change of lot, orvariations in the environment or the like.

As described above, the present invention permits the selection of theartificial fruit object 540 according to the change of the inspectedobject without changing the light projecting system and light receivingsystem and without rotating the artificial fruit object 540.

It should be noted that the present embodiment is just an example andthe present invention is by no means intended to be limited to this.

The required shape of the inside surface 500 of the artificial fruit orvegetable reference body 540 is one changing the thicknesses of the sidesurfaces 542 in the vertical direction of the vessel 546, which can berealized, for example, by a quadrangular pyramid or a circular cone. Theinside surface does not always have to be symmetric with respect to thevertical axis of the vessel 546 as long as it is inclined. Further, theinclination may also be made so as to decrease the thicknesses of theside surfaces 542 from the lid 550 side to the bottom side of the vessel546.

The other structure, operation, and effects than above are the same asin the first embodiment.

The thirteenth embodiment of the present invention will be describednext. Here, the same components as in the first embodiment or thetwelfth embodiment will be omitted from the description and differentportions will be described mainly.

FIG. 33 is a sectional view of an artificial fruit or vegetablereference body (artificial fruit object) 640 as the present embodiment.The present embodiment employs the artificial fruit object 640 in placeof the artificial fruit object 40 of the first embodiment or theartificial fruit object 540 of the twelfth embodiment and, asillustrated in FIG. 33, the inside surface 600 of the vessel 646 isformed in a stepped shape in the vertical direction. This makes thedistances between the side surfaces 642 stepwise narrower and narrowerfrom top to bottom of the vessel 646, while the thicknesses of the sidesurfaces 642 become stepwise thicker from top to bottom of the vessel646. When the light is projected from the direction T and emitted in thedirection U, the light projected to the upper part of the resin vessel646 travels through thin portions of the side surfaces 642 and through alonger portion of the light transmitting body 648 to the outside, whilethe light projected to the lower part of the resin vessel 646 travelsthrough thick portions of the side surfaces 642 and a shorter portion ofthe light transmitting body 648 to the outside. Namely, the lightprojected to the upper part of the resin vessel 646 is less affected bythe side surfaces 642 than the light projected to the lower part and isemitted at higher transmittances.

The other structure, operation, and effects than above are the same asin the first embodiment or the twelfth embodiment.

The fourteenth embodiment of the present invention will be describednext. Here, the same components as in the first embodiment will beomitted from the description and different portions will be describedmainly.

The present embodiment uses a shield plate 712 in place of the stop 66of the first embodiment. FIG. 34 is a perspective view to show thestructure of the projection optical system 702.

In the present embodiment the shield plate 712 has a plurality of, forexample two, circular, small holes 720. These small holes 720 haverespective diameters different from each other. When the light isprojected in the same projection amount from the lamp 710 disposedbehind the shield plate 712 to each small hole 720, light of an amountproportional to an aperture area of each small hole is emitted througheach small hole 720 from the front surface of the shield plate 712. Theshield plate 712 is arranged to be movable in the vertical directions Vby motor 730 and there are a plurality of small holes 720 provided alongthe moving directions V. Therefore, a desired small hole 720 can bepositioned on the optical axis of the lamp 710 and lens 714 by movingthe shield plate 712 in the vertical direction V by the motor 730.

Selection of the small hole 720 is made based on the kind of the fruitor vegetable being the inspected object 8. Namely, for measuring theinternal quality of a fruit or vegetable that is apt to transmit thelight easily, a small hole having a small diameter is used to decreasethe projection amount to the inspected object. On the other hand, in thecase of a fruit or vegetable that is resistant to transmission of thelight, a small hole having a large diameter is used to increase theprojection amount to the inspected object. In this way, the amount oflight emitted from the inspected object can be set so as to be not lessthan a fixed value, independent of the kind of the inspected object, byselecting a small hole 720 according to the kind of the inspected objectto change the amount of light projected to the inspected object. Thispermits accurate measurement of the internal quality of the fruits orvegetables independent of the kinds of the inspected objects.

Examples of the measurement in the present embodiment will be describedbelow.

A first example is the measurement of the internal quality of an orangeapt to transmit the light readily. A small hole having a small diameteris selected out of those in the shied plate 712. In this case, theinternal quality of the inspected object can be measured from theabsorption spectrum thereof, because the amount of light emitted fromthe inspected object is sufficiently large though the projection amountto the inspected body is small.

A second example is the measurement of the internal quality of an appleresistant to transmission of the light. A small hole having a largediameter is selected from those 720 of the shield plate 712. In thiscase, the internal quality of the inspected object 8 can be measuredfrom the absorption spectrum thereof, because the projection amount tothe inspected object is large and, therefore, the amount of lightemitted from the inspected object is sufficiently large.

The other measurement conditions than above are the same as in the caseof the inspected object being the orange, and the internal quality ofthe inspected object can be measured from the absorption spectrum of theemitted light from the inspected object.

A modification of the present embodiment will be described below.

The number of small holes 720 in the shield plate 712 can be any numberexcept for one.

In the present embodiment the shield plate 712 was arranged to be movedup or down in one way V and the small holes 720 were provided along theup or down direction V. The moving direction of the shield plate 712does not always have to be limited to the vertical direction V; forexample, the shield plate 712 can also be arranged to be movable in twoways, for example, in the vertical direction V and in a directionperpendicular to the vertical direction V within the plane including theshield plate 712. In this case, the small holes 720 can be formed atarbitrary positions in the shield plate 712 and a desired small hole 720can be positioned on the optical axis 718 of the lamp 710 by moving theshield plate 712 in the aforementioned two directions.

The shape of the small holes does not always have to be circular.

The control of the amount of the light projected to the inspected objectcan also be made with filters, instead of the small holes formed in theshield plate as in the present embodiment.

The other structure, operation, and effects than above are the same asin the first embodiment.

The fifteenth embodiment will be described below using FIG. 35. FIG. 35is a perspective view to show the structure of the projection opticalsystem 702 of the fifteenth embodiment.

In the present embodiment a circular shield plate 740 is placed in aplane normal to the optical axis 718 of the projection optical system702. The shield plate 740 is rotated about shaft 741 by motor 742connected to the shaft 741 extending normally from the center of theshield plate 740. In the shield plate 740 there are a plurality of, forexample two, circular, small holes 744 having different diameters atpositions an equal distance apart from the center of the shield plate740. This structure permits selection of a small hole 744 according tothe kind of the inspected object.

For measuring the internal quality of a fruit or vegetable apt totransmit the light easily, a small hole 744 having a small diameter isselected out of the small holes 744 in the shield plate 740. In thiscase, the internal quality of the inspected object can be measured fromthe absorption spectrum thereof, because the amount of light emittedfrom the inspected object is sufficiently large though the projectionamount to the inspected object is small. In contrast with it, formeasuring a fruit or vegetable resistant to transmission of the light, asmall hole having a large diameter is selected out of the small holes inthe shield plate 712. In this case, the internal quality of theinspected object can be measured from the absorption spectrum thereof,because the projection amount to the inspected object is large and thusthe amount of light emitted from the inspected object is sufficientlylarge.

The other structure and operation than above are the same as in thefourteenth embodiment.

The sixteenth embodiment will be described next.

In the sixteenth embodiment there is one fruit or vegetable or are aplurality of fruits or vegetables conveyed on the conveyor. In themiddle of the conveyor there are the projection optical system and themeasuring section with the spectroscope, similar to those in thefourteenth embodiment, on either side of the conveyor. Further, thepresent embodiment is provided with a photoelectric sensor upstream ofthe measuring section in the conveyance direction or within themeasuring section in the middle of the conveyor, so as to be capable ofmeasuring the size of each fruit or vegetable on the conveyor.

In the structure of the present embodiment, the photoelectric sensor candetect the size of each fruit or vegetable, and the light from the lampcan be automatically projected to the equator part of the inspectedobject, irrespective of the size of the inspected object, by moving theprojection optical system and spectroscope up and down according to theresult of the detection to change the height thereof.

Therefore, the internal quality of the inspected objects conveyedcontinuously can be measured at high speed under the same conditions.

The other structure and operation than above are the same as in thefirst embodiment.

The seventeenth embodiment of the present invention will be describedbelow referring to FIG. 36. Here, the description of the same componentsas in the first embodiment will be omitted and only different portionswill be described herein.

FIG. 36 is a sectional view to show an artificial fruit or vegetablereference body 760 (artificial fruit object) as an embodiment of thepresent invention. This artificial fruit object 760 is composed of acylindrical vinyl chloride vessel 751 having the diameter of 65 mm andthe height of 80 mm, a light transmitting body 752 retained therein, andan adhesive tape 770 adhered to a side surface of the vinyl chloridevessel 751 as a light scattering layer. The top surface of the vessel isalso covered by a vinyl chloride lid 754 to be closed hermetically.

In the present embodiment, the adhesive tape 770 is a resinous tape sothat a light irradiated to the artificial fruit object 760 is scatteredby the adhesive tape 770. The spectrum properties of the artificialfruit object 760 arranged as above follows the spectrum properties ofthe real fruits well.

Also, a heat-resistant glass 780 is provided around the side surface ofthe vessel 751 so as to surround the circumference of the adhesive tape770 and to be parallel to the side surface of the vessel. Theheat-resistant glass 780 is composed of two heat-resistant glass layersprovided in parallel to the side surface of the vessel with gap 782 ofabout 10 mm, and the gap is filled by 1% citric acid aqueous solution.With such arrangement, heat-resistant property is improved from the casewhere only the heat-resistance is provided.

The light transmitting body 752 contained in the vessel 751 is composedof 1% citric acid aqueous solution as an acid aqueous solution. Further,the artificial fruit object 760 of the present embodiment is providedwith a temperature measuring member (temperature measuring means) 753using a thermistor or the like for measuring the temperature of thelight transmitting body, inside the light transmitting body 752.

The present embodiment is just an example, so following modification canbe effected.

The material of the vessel 751 can be glass, polyethylene, orpolyfluoroethylene. The shape of the vessel 751 can be arbitrary shapedsuch as a rectangular parallelepiped.

The adhesive tape can include cellulose, so a paper tape can be used.Also, non-adhesive tape can be used. A polymer other than the resin canbe applied. Further, the light scattering layer can be provided on thesurface of the vessel 751 by coating, painting, spraying or dippinginstead of the adhesive tape. It is also preferable to adhere only to anoptical path portion of the light irradiated to the vessel 751.

The heat-resistant glass 780 can be arranged by one layer of glass tofill the aqueous solution between the side surface of the vessel and theglass layer. The heat-resistant glass 780 can be composed of three ormore glass layers. Also, the gap 782 can be formed in one layer of theheat-resistant glass. It is also preferable to provide only to anoptical path portion of the light irradiated to the vessel 751. A lighttransmitting heat-resistant material can be used instead of theheat-resistant glass 780.

An acid aqueous solution other than 1% citric acid aqueous solution, asugar aqueous solution or water can be used for the gap 782. Also, it ispreferable to flow the solution for improving heat-resistant property.Further, it is preferable to add a light scattering body into thesolution in the gap 782, and, in this arrangement, the adhesive tape 770can be omitted.

The other structure, operation, and effects than above are the same asin the first embodiment.

The present invention provides the apparatus for measuring the inspectedobjects arranged in the longitudinal direction of the belt of the beltconveyor, wherein a portion without an inspected object can be detectedin the longitudinal direction and the calibration of the apparatus canbe carried out at this portion. Therefore, the calibration can becarried out not only before the start of the measurement but also at adesired time after the start of the measurement. The measurement is notsuspended for the calibration. The internal quality of the fruits orvegetables can be measured accurately while the calibration of theapparatus is carried out without interrupting the measurementaccordingly.

According to the correction method of the present invention, an errordue to the environmental change in the measurement of the internalquality of fruits or vegetables can be corrected using the referencebody with variability of the absorption spectrum according to theenvironmental change and similar to the real inspected fruits orvegetables. The correction method is effective particularly againstchanges of the ambient temperature.

This obviates the need for the temperature control (management) of theapparatus or the ambient environment, thus reducing the cost thereof.

As described with FIG. 7, since the artificial fruit or vegetablereference body and the correction method using it according to thepresent invention also have the adequate follow-up property againstvariations in states of the light source, the measurement can also bestarted immediately after on of the light source without the need forwaiting for stabilization of the light source, thus enhancing themeasurement efficiency.

When the artificial fruit object is provided with the temperaturemeasuring means for monitoring the temperature of the transmitting bodyof the artificial fruit object, such as the thermistor, even if there isa difference between the temperatures of the artificial fruit object andthe inspected fruit or vegetable, correction can be made withconsideration thereto.

More accurate correction can also be made by carrying out the correctionwith a plurality of artificial fruit objects having respectiveconcentrations.

When the light diffusing body is mixed in the aqueous solution in theartificial fruit or vegetable reference body of the present invention,the artificial fruit or vegetable reference body can have an appropriatevalue of light transmittance. The transmittance can be adjusted readilyby adjusting the concentration of the light diffusing body.

When the gelling agent is added to the aqueous solution in theartificial fruit object of the present invention to make the solutiongel, the artificial fruit object can be stabilized without sedimentationof the light diffusing body.

The measuring device of the internal quality of fruits or vegetablesaccording to the present invention can measure the internal qualitycorrected for fluctuations of the absorption spectrum of the fruits orvegetables due to the environmental change, because it is provided withthe artificial fruit or vegetable reference body.

When the device is provided with a plurality of artificial fruit orvegetable reference bodies, the reference bodies having respectivedifferent concentrations, more accurate correction can be realizedaccording to the concentration of each inspected fruit or vegetable.

In the present invention, the light can be projected to the vicinity ofthe equator part of each inspected object, irrespective of the size ofthe inspected object. Therefore, the internal quality of each inspectedobject can be measured under the same conditions, thereby enhancing thereliability of measured data. The amount of the projected light to thefruit or vegetable can be varied according to the kind of the fruit orvegetable being the inspected object. Since the absorption spectrum canbe measured for the inspected objects resistant to transmission of thelight, the internal quality of the fruits or vegetables can be measuredmore accurately, independent of the kind of the inspected objects,accordingly.

In the present invention the position of the inspected object on themoving means is detected on the upstream side of the measurementposition in the moving path of the inspected object and the movingamount of the moving means is monitored, whereby the measurement can becarried out when the inspected object is correctly located at themeasurement position, thereby enhancing the measurement accuracy.

The position of the inspected object on the moving means is detectedboth upstream and downstream of the measurement position in the movingpath of the inspected object and an event with a deviation between themis determined as a measurement error. Therefore, an inspected objectwith doubtful measurement accuracy can be recognized and it is alsopossible to apply the process for re-measuring the doubtful inspectedobject, which assures the measurement with higher reliability.

The present invention can provide the apparatus for measuring theinspected objects arranged in the longitudinal direction of the beltconveyor, wherein a portion without an inspected object can be measuredin the longitudinal direction and the calibration of the apparatus canbe carried out at this portion. Therefore, the calibration can becarried out not only before the start of the measurement but also at adesired time after the start of the measurement, and the measurement isnot interrupted by the calibration. The internal quality of the fruit orvegetable can be measured accurately by carrying out the calibration ofthe apparatus at an arbitrary time without interruption of themeasurement accordingly.

Since the device of the present invention is arranged to project thelight from the side to the inspected object and receive the transmittedlight above the inspected object, it can secure the amount of thetransmitted light equivalent to those of the conventional devices of thelower reception type while being free of the restrictions on theconveying system as forced in the lower reception type. Therefore, thedevice of the present invention also permits the random measurement withthe inspected objects being supplied at random onto the conveyor, so asto enable continuous measurement at high efficiency. Since the lightreceiving means can be installed in the space above the device wherethere is no interfering object, this facilitates assembling andmaintenance.

When the shield plate is disposed beside the inspected object located atthe measurement position and at the position lower than the height ofthe inspected object and higher than the projection position of thelight from the light projecting means onto the inspected object, thelight receiving means can be effectively shielded from the stray light.

In the configuration in which the light projecting means is positionedon the both sides of the moving means, if there are a pair of shieldplates provided on the both sides and the separation between the twoshield plates is adjustable, the clearance between the shield plates andthe inspected object can be adjusted according to the measured objectwithout interference therewith, so as to achieve effective shielding.Further, when the device is provided with the lateral diameter measuringmeans disposed upstream of the measurement position in the moving pathand arranged to measure the lateral diameter of the inspected object,and the adjusting means for adjusting the separation between the shieldplates, based on the output of the lateral diameter measuring means, itbecomes possible to adjust the shield plates according to the sizes ofthe individual inspected objects.

In the device of the present invention, the stray light can beeffectively intercepted when the shield plates are positioned above theheight of the inspected object located at the measurement position.Further, when the device is provided with the height measuring meansdisposed upstream of the predetermined position in the moving path andarranged to measure the height of the inspected object, and theadjusting means for adjusting the height of the shield plates, based onthe output of the height measuring means, the shield plates can be setat the position where effective shielding can be achieved withoutinterference with the inspected object, according to the heights of theindividual inspected objects.

When the device of the present invention is provided with the sizemeasuring means disposed upstream of the measurement position in themoving path and arranged to measure at least one of the height and thelateral diameter of the inspected object, the shield plate for shieldingthe light receiving means from the light directly projected from thelight projecting means and from the light reflected by the surface ofthe inspected object, the shield plate being disposed near the inspectedobject at the measurement position and being capable of being pivotedabout the predetermined horizontal axis, and the adjusting means foradjusting the angular position about the horizontal axis of the shieldplate, based on the output from the size measuring means, so as todecrease the gap between the shield plate and the inspected object atthe predetermined position, effective shielding can be achievedaccording to the size of each inspected object.

When the device of the present invention is provided with the shieldplate for shielding the light receiving means from the light directlyprojected from the light projecting means and from the light reflectedby the surface of the inspected object, the shield plate being capableof being pivoted about the predetermined horizontal axis, the shieldplate being pushed up by the inspected object to be pivoted about thehorizontal axis as the inspected object is moved by the moving means toapproach the predetermined position and the shield plate shielding thelight receiving means from the light while being in contact with theinspected object when the inspected object is located at thepredetermined position, effective shielding can be achieved by thesimple structure. In this case, if the shield plate is provided with theupward curl for allowing the shield plate to be moved up when it touchesthe inspected object, at the corner on the upstream side of the movingpath in the shield plate and on the contact side with the inspectedobject, the shield plate can be pushed up on a smooth basis by theinspected object without being caught by the inspected object.

When the device of the present invention is provided with the tray fixedon the moving means and arranged to accommodate the inspected object,the tray covering at least part of the inspected object accommodatedtherein and having the aperture opening so as to let the light from thelight projecting means reach the inspected object, the stray light canbe intercepted effectively.

What is claimed is:
 1. An internal quality measuring apparatus formeasuring an internal quality of an object, said measuringcomprising:conveying means for continuously conveying an object;detecting means for detecting a position of the object mounted on saidconveying means; light projecting means for projecting measurement lightto the object; light receiving means for receiving light having beentransmitted through the object; analyzing means for analyzing theinternal quality of the object with the light received by said lightreceiving means; and reference body interposing means for interposing areference body having a predetermined optical property in an opticalpath between said light projecting means and light receiving means,based on a signal from said detecting means; wherein said analyzingmeans compares light received with the reference body being interposed,with reference data preliminarily stored, and corrects a result of theanalysis, based thereon.
 2. The internal quality measuring apparatusaccording to claim 1, wherein the reference body is an optical filterhaving a specific optical property.
 3. The internal quality measuringapparatus according to claim 1, wherein the reference body is apseudo-object member.
 4. The internal quality measuring apparatusaccording to claim 1, further comprising shield means for interceptingthe light incident to said light receiving means,wherein while it isdetermined based on the detection by said detecting means that a spacingbetween objects on said conveying means is less than a predeterminedvalue, said reference body interposing means allows the light from saidlight projecting means to be projected onto the object withoutintervention of the reference body, so as to allow said light receivingmeans to measure the light having been transmitted through the object;and wherein when it is determined based on the detection by saiddetecting means that the spacing between the objects on said conveyingmeans is not less than the predetermined value, said reference bodyinterposing means interposes the reference body in the optical pathbetween said light projecting means and said light receiving means, soas to adjust an amount of light incident to said light receiving meansand allow said light receiving means to measure the amount of the lightthus adjusted; said measuring device further comprising: arithmeticoperation means for correcting a result of the measurement by said lightreceiving means, based on a result of measurement by said lightreceiving means when the amount of the incident light is controlled bysaid reference body interposing means and a result of measurement bysaid light receiving means when the incident light is intercepted bysaid shield means.
 5. The internal quality measuring apparatus accordingto claim 4, wherein when it is determined based on the detection by saiddetecting means that the spacing between the objects on said conveyingmeans is not less than the predetermined value, reference bodyinterposing means adjust the amount of the light incident to said lightreceiving means, said light receiving means measures the amount of thelight thus adjusted, thereafter further said shield means intercepts thelight incident to said light receiving means, and said light receivingmeans measures the amount of the light in this state; orsaid shieldmeans intercept the light incident to said light receiving means, saidlight receiving means measures the amount of the light in this state,thereafter the intercepting state of the light incident to said lightreceiving means by said shield means is released, said reference bodyinterposing means adjusts the amount of the light incident to said lightreceiving means, and said light receiving means measure the amount ofthe light thus adjusted.
 6. The internal quality measuring apparatusaccording to claim 3, wherein said pseudo-object member comprises atransparent vessel and a light transmitting body comprised of an aqueoussolution retained in said vessel.
 7. The internal quality measuringapparatus according to claim 6, wherein said light transmitting body iscomprised of a light scattering body mixed in the aqueous solution. 8.The internal quality measuring apparatus according to claim 7, whereinat least one side surface out of side surfaces of said transparentvessel has a thickness different from that of the other side surfaces.9. The internal quality measuring apparatus according to claim 7,wherein thicknesses of the side surfaces opposed to each other out ofthe side surfaces of said transparent vessel are equal and thicknessesof the side surfaces adjacent to each other are different from eachother.
 10. The internal quality measuring apparatus according to claim6, wherein side surfaces of said transparent vessel have a samethickness.
 11. The internal quality measuring apparatus according toclaim 6 or 7, wherein said transparent vessel includes glass.
 12. Theinternal quality measuring apparatus according to claim 6 or 7, whereinsaid transparent vessel includes vinyl chloride.
 13. The internalquality measuring apparatus according to claim 6 or 7, wherein saidtransparent vessel contains polyethylene.
 14. The internal qualitymeasuring apparatus according to claim 6 or 7, wherein said transparentvessel contains polyfluoroethylene.
 15. The internal quality measuringapparatus according to claim 14, wherein said transparent vesselcontains graphite.
 16. The internal quality measuring apparatusaccording to claim 6, wherein at least one side surface of saidtransparent vessel is provided with a light scattering layer.
 17. Theinternal quality measuring apparatus according to claim 16, wherein saidlight scattering layer includes resin.
 18. The internal qualitymeasuring apparatus according to claim 16, wherein said light scatteringlayer includes cellulose.
 19. The internal quality measuring apparatusaccording to claim 17 or 18, wherein said light scattering layer is anadhesive tape.
 20. The internal quality measuring apparatus according toclaim 17 or 18, wherein said light scattering layer is formed bycoating.
 21. The internal quality measuring apparatus according to claim6, wherein at least one side surface of said transparent vessel isprovided with a heat-resistant glass plate.
 22. The internal qualitymeasuring apparatus according to claim 6, wherein at least one sidesurface of said transparent vessel is provided with a heat-resistantglass plate.
 23. The internal quality measuring apparatus according toclaim 21 or 22, wherein the heat-resistant glass plate includes pluralheat-resistant glass layers, and a water layer is provided in at leastone of gaps between the heat-resistant glass layers.
 24. The internalquality measuring apparatus according to claim 21 or 22, wherein theheat-resistant glass plate includes plural heat-resistant glass layers,and an acid aqueous solution layer is provided in at least one of gapsbetween the heat-resistant glass layers.
 25. The internal qualitymeasuring apparatus according to claim 21 or 22, wherein theheat-resistant glass plate includes plural heat-resistant glass layers,and an sugar aqueous solution layer is provided in at least one of gapsbetween the heat-resistant glass layers.
 26. The internal qualitymeasuring apparatus according to claim 21, wherein a water layer isprovided between said transparent vessel and the heat-resistant glassplate.
 27. The internal quality measuring apparatus according to claim21, wherein an acid aqueous solution layer is provided between saidtransparent vessel and the heat-resistant glass plate.
 28. The internalquality measuring apparatus according to claim 21, wherein a sugaraqueous solution layer is provided between said transparent vessel andthe heat-resistant glass plate.
 29. The internal quality measuringapparatus according to claim 6 or 7, wherein said transparent vessel isrotatable about an axis being parallel to a direction of a height of thetransparent vessel and passing a center of a bottom surface thereof. 30.The internal quality measuring apparatus according to claim 6 or 7,wherein said transparent vessel is rotatable about an axis parallel to adirection of a height of the transparent vessel.
 31. The internalquality measuring apparatus according to claim 6 or 7, wherein saidtransparent vessel is rotatable about an axis that is horizontal andnormal to an optical axis of the measurement light projected from saidlight projecting means.
 32. The internal quality measuring apparatusaccording to claim 3, wherein said pseudo-object member comprises atransparent vessel and a light transmitting body retained in the vessel,said light transmitting body being a substance obtained by dispersing alight scattering body in an aqueous solution and adding a gelling agentthereto to make the solution gel.
 33. The internal quality measuringapparatus according to claim 6 or 7, wherein said pseudo-object membercomprises temperature measuring means for measuring a temperature ofsaid light transmitting body.
 34. The internal quality measuringapparatus according to claim 6 or 7, wherein said aqueous solution is anaqueous solution of an acid.
 35. The internal quality measuringapparatus according to claim 34, wherein said acid is citric acid. 36.The internal quality measuring apparatus according to claim 6 or 7,wherein said aqueous solution is an aqueous solution of a sugar.
 37. Theinternal quality measuring apparatus according to claim 36, wherein saidsugar is cane sugar.
 38. The internal quality measuring apparatusaccording to claim 7, wherein the light scattering body is fine powderhaving a floating property.
 39. The internal quality measuring apparatusaccording to claim 7, wherein the light scattering body is colloidalparticles.
 40. The internal quality measuring apparatus according toclaim 38 or 39, wherein the light scattering body is cerium oxide. 41.The internal quality measuring apparatus according to claim 38 or 39,wherein the light scattering body is titanium oxide.
 42. The internalquality measuring apparatus according to claim 6,wherein said lightprojecting means projects light toward the object at a predeterminedposition in a moving path of the object by the conveying means, andlight receiving means is disposed near said predetermined position andreceives light emitted from the object located at said predeterminedposition, and the pseudo-object member is set at said predeterminedposition during a correction operation, to correct measurement of theinternal quality by using the pseudo-object member.
 43. The internalquality measuring apparatus according to claim 42, further comprisingmoving up-and-down means for moving said pseudo-object member up anddown between a down position where said pseudo-object member is locatedat said predetermined position and an up position where thepseudo-object member is retracted from said predetermined position. 44.The internal quality measuring apparatus according to claim 6 or 7,wherein the reference body includes a plurality of pseudo-objectmembers, wherein concentrations of said aqueous solution in saidplurality of pseudo-object members are different from each other, andwherein measurement of the internal quality of the object is correctedusing the plurality of pseudo-object members.
 45. The internal qualitymeasuring apparatus according to claim 44, wherein said plurality ofpseudo-object members is mounted on a revolver member rotatable about apredetermined axis and wherein during a correction operation of theapparatus the pseudo-object members are positioned in order between saidlight projecting means and said light receiving means with rotation ofsaid revolver member.
 46. The internal quality measuring apparatusaccording to claim 45, wherein said revolver member has a through holeand during normal measurement except for said correction operation thelight from said light projecting means is projected through the throughhole to the object.
 47. The internal quality measuring apparatusaccording to claim 1, further comprising:projection light amount controlmeans for controlling a projection light amount according to a kind ofthe object; and position control means for controlling locations of saidlight projecting means, said conveying means, and said light receivingmeans, according to a size of the object.
 48. The internal qualitymeasuring apparatus according to claim 47, wherein said projection lightamount control means comprises a stop and a size of an aperture of saidstop is varied according to the size of the object.
 49. The internalquality measuring apparatus according to claim 48, wherein saidprojection light amount control means comprises a shield plate having aplurality of small holes and shield plate moving means for moving saidshield plate, andwherein one of said small holes is located by saidshield plate moving means on an optical axis of said light projectingmeans and between said light projecting means and the object, accordingto the size of the object.
 50. The internal quality measuring apparatusaccording to claim 49, wherein said shield plate is of a rectangularshape, a plurality of small holes are provided on an arbitrary straightline within a surface of the shield plate, and said shield plate isarranged to be moved on the straight line by said shield plate movingmeans.
 51. The internal quality measuring apparatus according to claim49, wherein said shield plate is of a circular shape, a plurality of thesmall holes are provided at positions an equal distance apart from thecenter of the circle within a surface of the shield plate, and saidshield plate is arranged to be rotated about the center by said shieldplate moving means.
 52. The internal quality measuring apparatusaccording to claim 47, further comprising diameter detecting means fordetecting a diameter of the object,wherein said light projecting meansprojects the light to a region around an equator part of the objectconveyed while said position control means controls the locations ofsaid light projecting means, said conveying means, and said lightreceiving means, based on a result of the detection of the diameter bysaid diameter detecting means.
 53. The internal quality measuringapparatus according to claim 1, further comprising:upstream detectingmeans disposed upstream of said light receiving means and arranged todetect a position of the object on said conveying means, in a conveyancepath by said conveying means; monitor means for monitoring a movingamount of said conveying means; and control means for performing such acontrol that the light receiving means receives the light when saidobject on the conveying means passes a light receiving position of saidlight receiving means, based on outputs from said upstream detectingmeans and said monitor means.
 54. The internal quality measuringapparatus according to claim 53, wherein said upstream detecting meansdetects a lateral diameter in a conveying direction of the object andwherein said control means calculates a center position in the conveyingdirection of the object, based on the lateral diameter detected and saidcontrol means performs such a control that the light receiving meansreceives the light when the center of the object passes the lightreceiving position of the light receiving means.
 55. The internalquality measuring apparatus according to claim 53, furthercomprising:downstream detecting means disposed downstream of said lightreceiving means in said conveyance path and arranged to detect aposition of the object on said conveying means; and error determiningmeans for comparing the position of the object on the conveying means,detected by said upstream detecting means, with the position of the sameobject on the conveying means, detected by said downstream detectingmeans, and for determining that a measurement error was made, when thereis a deviation between the two positions.
 56. The internal qualitymeasuring apparatus according to claim 54, further comprising:downstreamdetecting means disposed downstream of said light receiving means insaid conveyance path and arranged to detect a position of the object onsaid conveying means; and error determining means for comparing theposition of the object on the conveying means, detected by said upstreamdetecting means, with the position of the same object on the conveyingmeans, detected by said downstream detecting means, and for determiningthat a measurement error was made, when there is a deviation between thetwo positions.
 57. The internal quality measuring apparatus according toclaim 54, further comprising:downstream detecting means disposeddownstream of said light receiving means in said conveyance path andarranged to detect a lateral diameter of said object in the conveyingdirection; and error determining means for comparing a lateral diameterof the object in the conveying direction, detected by said upstreamdetecting means, with a lateral direction of the object in the movingdirection, detected by said downstream detecting means, and fordetermining that a measurement error was made, when there is a deviationbetween the two lateral diameters.
 58. The internal quality measuringapparatus according to claim 55, further comprising classifying meansfor classifying an object with which said error determining meansdetermined that a measurement error was made, as an object to bemeasured again.
 59. The internal quality measuring apparatus accordingto claim 56, further comprising classifying means for classifying anobject with which said error determining means determined that ameasurement error was made, as an object to be measured again.
 60. Theinternal quality measuring apparatus according to claim 57, furthercomprising classifying means for classifying an object with which saiderror determining means determined that a measurement error was made, asan object to be measured again.
 61. The internal quality measuringapparatus according to claim 1, further comprising:a first optical fiberhaving one end located at a position where the light projected from saidlight projecting means can be received directly and the other endconnected to said light receiving means, said first optical fiberreceiving the light from said light projecting means withoutintervention of the object; light amount adjusting means disposed at theend or in the middle of an optical path of said first optical fiber andarranged to adjust an amount of light passing through said first opticalfiber; first shield means disposed at the end or in the middle of theoptical path of said first optical fiber and arranged to intercept thelight passing through said first optical fiber; a second optical fiberhaving one end located at a position where the light emitted from theobject can be received and the other end connected to said lightreceiving means, said second optical fiber receiving the light havingbeen transmitted by the object; second shield means disposed at the endor in the middle of an optical path of said second optical fiber andarranged to intercept light passing through said second optical fiber;and control means for controlling operations of said first shield meansand said second shield means, based on the result of the detection bysaid detecting means; wherein while it is determined based on thedetection by said detecting means that a spacing between objects on saidconveying means is less than a predetermined value, said control meansmakes said first shield means shield said first optical fiber and makessaid light receiving means measure the light incident thereto from saidsecond optical fiber; wherein when it is determined based on thedetection by said detecting means that the spacing between the objectson said conveying means is not less than the predetermined value, saidcontrol means makes said second shield means shield said second opticalfiber and makes said light receiving means measure the light incidentthereto from said first optical fiber through said light amountadjusting means; said measuring device further comprising: arithmeticoperation means for correcting a result of the measurement by said lightreceiving means, based on a result of measurement by said lightreceiving means when the amount of the incident light is controlled bysaid control means and a result of measurement by said light receivingmeans when said shield means intercepts the incident light.
 62. Theinternal quality measuring apparatus according to claim 61, furthercomprising measuring means for making said second shield means shieldsaid second optical fiber at an arbitrary time, irrespective of theresult of the detection by said detecting means, and making said lightreceiving means measure the light incident thereto from said firstoptical fiber through said light amount adjusting means.
 63. Theinternal quality measuring apparatus according to claim 62, wherein whenit is determined based on the detection by said detecting means that thespacing between the objects on said conveying means is not less than thepredetermined value, said second shield means is made to shield saidsecond optical fiber, said light receiving means is made to measure thelight incident thereto from said first optical fiber through said lightamount adjusting means, thereafter said first shield means is furthermade to shield said first optical fiber, and said light receiving meansis made to measure the light with said first optical fiber and saidsecond optical fiber being in a shielded state; or said first shieldmeans and said second shield means are made to shield said first opticalfiber and said second optical fiber, said light receiving means is madeto measure the light with said first optical fiber and said secondoptical fiber being in the shielded state, thereafter said first shieldmeans is opened to open said first optical fiber, and said lightreceiving means is made to measure the light incident thereto from saidfirst optical fiber through said light amount adjusting means.
 64. Theinternal quality measuring apparatus according to claim 1, wherein saidlight projecting means projects the light from the side of the object ata predetermined position in the moving path of the object and whereinsaid light receiving means is disposed above the object at thepredetermined position and receives the light having been transmittedupward by the object.
 65. The internal quality measuring apparatusaccording to claim 64, further comprising a shield plate located besidethe object at said predetermined position and at a position lower than aheight of the object and higher than a projection light position of thelight from said light projecting means onto the object, said shieldplate being provided for shielding said light receiving means from straylight.
 66. The internal quality measuring apparatus according to claim65, wherein said light projecting means and shield plates are disposedon either side of said moving means and a separation between the twoshield plates is adjustable.
 67. The internal quality measuringapparatus according to claim 66, further comprising lateral diametermeasuring means disposed upstream of said predetermined position in saidmoving path and arranged to measure a lateral diameter of said object,and adjusting means for adjusting the separation between said shieldplates, based on an output from the lateral diameter measuring means.68. The internal quality measuring apparatus according to claim 64,further comprising a shield plate disposed at a height higher than aheight of the object at said predetermined position and arranged toshield said light receiving means from stray light.
 69. The internalquality measuring apparatus according to claim 68, further comprisingheight measuring means disposed upstream of said predetermined positionin said moving path and arranged to measure the height of said object,and adjusting means for adjusting the height of said shield plate, basedon an output from the height measuring means.
 70. The internal qualitymeasuring apparatus according to claim 64, further comprising sizemeasuring means disposed upstream of said predetermined position in saidmoving path and arranged to measure at least one of a height and alateral diameter of said object, a shield plate for shielding said lightreceiving means from stray light, said shield plate being disposed nearthe object at said predetermined position and being capable of beingpivoted about a predetermined horizontal axis, and adjusting means foradjusting an angular position about said horizontal axis of said shieldplate, based on an output from said size measuring means, so as todecrease a gap between said shield plate and the object at saidpredetermined position.
 71. The internal quality measuring apparatusaccording to claim 64, further comprising a shield plate for shieldingsaid light receiving means from stray light, said shield plate beingdisposed near the object at said predetermined position and beingcapable of being pivoted about a predetermined horizontal axis, saidshield plate being pushed up by the object to be pivoted about saidhorizontal axis as said object is moved by said moving means to approachsaid predetermined position, whereby the shield plate shields the lightreceiving means from the stray light with being in a contact state withthe object when the object is located at said predetermined position.72. The internal quality measuring apparatus according to claim 71,wherein said shield plate is provided with an upward curl for permittingthe shield plate to move away when it touches the object, at a corner onthe upstream side of said moving path and on the contact side with theobject in said shield plate.
 73. The internal quality measuringapparatus according to claim 64, further comprising a tray fixed on saidmoving means and arranged to receive said object, said tray covering atleast part of the object received thereon and having an aperture boredso as to permit the light from said light projecting means to reach theobject.
 74. An internal quality measuring apparatus for measuring aninternal quality of an object, said measuring apparatuscomprising:conveying means for continuously conveying an object;detecting means for detecting a spacing between objects mounted on saidconveying means; light projecting means for projecting light to theobject; light receiving means for measuring light having beentransmitted by the object; shield means for intercepting the lightincident to said light receiving means; light amount adjusting means foradjusting an amount of the light projected from said light projectingmeans; and control means for controlling an amount of the light incidentto said light receiving means, based on a result of the detection bysaid detecting means; wherein while it is determined based on thedetection by said detecting means that the spacing between the objectson said conveying means is less than a predetermined value, said controlmeans makes said light projecting means project the light to the objectwithout intervention of said light amount adjusting means and makes thelight receiving means measure the light having been transmitted throughthe object; wherein when it is determined based on the detection by saiddetecting means that the spacing between the objects on said conveyingmeans is not less than the predetermined value, said control means makessaid light amount adjusting means adjust the amount of the lightincident to said light receiving means and makes said light receivingmeans measure the amount of the light thus adjusted; said measuringdevice further comprising arithmetic operation means for correcting aresult of the measurement by said light receiving means, based on aresult of measurement by said light receiving means when said controlmeans controls the amount of the incident light and a result ofmeasurement by said light receiving means when said shield meansintercepts the incident light.
 75. The internal quality measuringapparatus according to claim 74,wherein when it is determined based onthe detection by said detecting means that the spacing between theobjects on said conveying means is not less than the predeterminedvalue, said control means makes said light amount adjusting means adjustthe amount of the light incident to said light receiving means, makessaid light receiving means measure the amount of the light thusadjusted, thereafter further makes said shield means intercept the lightincident to said light receiving means, and makes said light receivingmeans measure an amount of light in this state; or said control meansmakes said shield means intercept the light incident to said lightreceiving means, makes said light receiving means measure the amount oflight in this state, thereafter releases said shield means from theintercepting state of the light incident to said light receiving means,makes said light amount adjusting means adjust the amount of the lightincident to said light receiving means, and makes said light receivingmeans measure the amount of the light thus adjusted.
 76. A correctionmethod for measurement of an internal quality of an object, themeasurement comprising steps of radiating light toward the object andanalyzing light scattered inside the object and emitted from the objectby spectral analysis, said correction method comprising:a step ofcarrying out the measurement with a pseudo-object member containing anaqueous solution obtained by dissolving a solute in water, and a step ofcorrecting a result of the measurement of the object, based on a resultof the measurement with the pseudo-object member.
 77. The correctionmethod according to claim 76, wherein a light diffusing body is mixed insaid aqueous solution.
 78. The correction method according to claim 76or 77, wherein said correction is carried out based on a differencebetween a value obtained in the measurement with said pseudo-objectmember and a predetermined reference value.
 79. The correction methodaccording to claim 76 or 77, further comprising steps of measuring atemperature of said pseudo-object member and further carrying out thecorrection based on a result of the measurement of the temperature. 80.The correction method according to claim 76 or 77, wherein said soluteis an acid.
 81. The correction method according to claim 80, whereinsaid acid is citric acid.
 82. The correction method according to claim76 or 77, wherein said solute is a sugar.
 83. The correction methodaccording to claim 82, wherein said sugar is cane sugar.
 84. Thecorrection method according to claim 76 or 77, wherein said solute is anacid and a sugar.
 85. An internal quality measuring apparatus formeasuring an internal quality of an object on a non-destructive basis,said measuring apparatus comprising:light projecting means forprojecting light toward an object; support means for supporting theobject; measuring means for measuring light having been transmittedthrough the object; projection light amount control means forcontrolling a projection light amount according to a kind of the object,said projection light amount control means comprising a shield platehaving a plurality of small holes and shield plate moving means formoving said shield plate, one of said small holes being located by saidshield plate moving means on an optical axis of said light projectingmeans and the object, according to the size of the object; and positioncontrol means for controlling locations of said light projecting means,said support means, and said measuring means, according to a size of theobject.
 86. The internal quality measuring apparatus according to claim85, wherein said shield plate is of a rectangular shape, a plurality ofthe small holes are provided on an arbitrary straight line within asurface of the shield plate, and said shield plate is arranged to bemoved on the straight line by said shield plate moving means.
 87. Theinternal quality measuring apparatus according to claim 85, wherein saidshield plate is of a circular shape, a plurality of the small holes areprovided at positions an equal distance apart from the center of thecircle within a surface of the shield plate, and said shield plate isarranged to be rotated about the center by said shield plate movingmeans.
 88. An internal quality measuring apparatus for measuring aninternal quality of an object on a non-destructive basis, said measuringapparatus comprising:light projecting means for projecting light towardan object; support means for supporting the object; measuring means formeasuring light having been transmitted through the object; projectionlight amount control means for controlling a projection light amountaccording to a kind of the object; position control means forcontrolling locations of said light projecting means, said supportmeans, and said measuring means, according to a size of the object;conveying means for continuously conveying the object; and detectingmeans for detecting a diameter of the object, wherein said lightprojecting means projects the light to a region around an equator partof the object conveyed while said position control means controls thelocations of said light projecting means, said support means, and saidmeasuring means, based on a result of the detection by said detectingmeans.
 89. An internal quality measuring apparatus comprising:movingmeans for moving objects mounted at random thereon; and measuring meansdisposed in a moving path of the objects by the moving means andarranged to project light toward an object under movement and measurelight having been transmitted through the object, wherein an internalquality of the object is measured based on an output from the measuringmeans, said measuring apparatus comprising: upstream detecting meansdisposed upstream of said measuring means in said moving path andarranged to detect a position of the object on said moving means;monitor means for monitoring a moving amount of said moving means; andcontrol means for performing such a control that the measuring meansperforms the measurement when said object on the moving means passes ameasurement position of said measuring means, based on outputs from saidupstream detecting means and said monitor means.
 90. The internalquality measuring apparatus according to claim 89, wherein said upstreamdetecting means detects a lateral diameter in a moving direction of theobject and wherein said control means calculates a center position inthe moving direction of the object, based on the lateral diameterdetected, and said control means performs such a control that themeasuring means performs the measurement when the center of the objectpasses the measurement position of the measuring means.
 91. The internalquality measuring apparatus according to claim 89 or 90, furthercomprising:downstream detecting means disposed downstream of saidmeasuring means in said moving path and arranged to detect a position ofthe object on said moving means; and error determining means forcomparing the position of the object on the moving means, detected bysaid upstream detecting means, with the position of the same object onthe moving means, detected by said downstream detecting means, and fordetermining that a measurement error was made, when there is a deviationbetween the two positions.
 92. The internal quality measuring apparatusaccording to claim 90, further comprising:downstream detecting meansdisposed downstream of said measuring means in said moving path andarranged to detect a lateral diameter of said object in the movingdirection; and error determining means for comparing a lateral diameterof the object in the moving direction, detected by said upstreamdetecting means, with a lateral direction of the object in the movingdirection, detected by said downstream detecting means, and fordetermining that a measurement error was made, when there is a deviationbetween the two lateral diameters.
 93. The internal quality measuringapparatus according to claim 92, further comprising classifying meansfor classifying an object with which said error determining meansdetermined that a measurement error was made, as an object to bemeasured again.
 94. A control method for controlling an internal qualitymeasuring apparatus comprising:moving means for moving objects mountedat random thereon; and measuring means disposed in a moving path of theobjects by the moving means and arranged to project light toward anobject under movement and measure light having been transmitted throughthe object, wherein an internal quality of the object is measured basedon an output from the measuring means, said control method comprising: astep of detecting a position of said object on said moving means on anupstream side of an object measurement position by said measuring meansin said moving path; a step of detecting a position of said object onsaid moving means on a downstream side of the object measurementposition by said measuring means in said moving path; and a step ofdetermining that a measurement error was made, when there is a deviationbetween said position detected on the upstream side and said positiondetected on the downstream side.
 95. An internal quality measuringapparatus for evaluating an internal quality of an object thereto, saidmeasuring apparatus comprising:moving means for moving an object mountedthereon; light projecting means for projecting light from the side ofthe object thereto, at a predetermined position in a moving path of theobject by the moving means; light receiving means disposed above theobject at said predetermined position and arranged to receive lighthaving been transmitted upward by the object; and a shield plate locatedbeside the object at said predetermined position and at a position lowerthan a height of the object and higher than a projection light positionof the light from said light projecting means onto the object, saidshield plate being provided for shielding said light receiving meansfrom stray lights wherein the internal quality of the object isevaluated based on light incident to said light receiving means.
 96. Theinternal quality measuring apparatus according to claim 95, wherein saidlight projecting means and shield plates are disposed on either side ofsaid moving means and a separation between the two shield plates isadjustable.
 97. The internal quality measuring apparatus according toclaim 96, further comprising lateral diameter measuring means disposedupstream of said predetermined position in said moving path and arrangedto measure a lateral diameter of said object, and adjusting means foradjusting the separation between said shield plates, based on an outputfrom the lateral diameter measuring means.
 98. An internal qualitymeasuring apparatus for evaluating an internal quality of an objectthereto, said measuring apparatus comprising:moving means for moving anobject mounted thereon; light projecting means for projecting light fromthe side of the object thereto, at a predetermined position in a movingpath of the object by the moving means; light receiving means disposedabove the object at said predetermined position and arranged to receivelight having been transmitted upward by the object; and a shield platedisposed at a height higher than a height of the object at saidpredetermined position and arranged to shield said light receiving meansfrom stray light, wherein the internal quality of the object isevaluated based on light incident to said light receiving means.
 99. Theinternal quality measuring apparatus according to claim 98, furthercomprising height measuring means disposed upstream of saidpredetermined position in said moving path and arranged to measure aheight of said object, and adjusting means for adjusting the height ofsaid shield plate, based on an output from the height measuring means.100. An internal quality measuring apparatus for evaluating an internalquality of an object thereto, said measuring apparatus comprising:movingmeans for moving an object mounted thereon; light projecting means forprojecting light from the side of the object thereto, at a predeterminedposition in a moving path of the object by the moving means; lightreceiving means disposed above the object at said predetermined positionand arranged to receive light having been transmitted upward by theobject; size measuring means disposed upstream of said predeterminedposition in said moving path and arranged to measure at least one of aheight and a lateral diameter of said object; a shield plate forshielding said light receiving means from stray light, said shield platebeing disposed near the object at said predetermined position and beingcapable of being pivoted about a predetermined horizontal axis; andadjusting means for adjusting an angular position about said horizontalaxis of said shield plate, based on an output from said size measuringmeans, so as to decrease a gap between said shield plate and the objectat said predetermined position, wherein the internal quality of theobject is evaluated based on light incident to said light receivingmeans.
 101. An internal quality measuring apparatus for evaluating aninternal quality of an object thereto, said measuring apparatuscomprising:moving means for moving an object mounted thereon; lightprotecting means for projecting light from the side of the objectthereto, at a predetermined position in a moving path of the object bythe moving means; light receiving means disposed above the object atsaid predetermined position and arranged to receive light having beentransmitted upward by the object; and a shield plate for shielding saidlight receiving means from stray light, said shield plate being disposednear the object at said predetermined position and being capable ofbeing pivoted about a predetermined horizontal axis, said shield platebeing pushed up by the object to be pivoted about said horizontal axisas said object is moved by said moving means to approach saidpredetermined position, whereby the shield plate shields the lightreceiving means from the stray light with being in a contact state withthe object when the object is located at said predetermined position,wherein the internal quality of the object is evaluated based on lightincident to said light receiving means.
 102. The internal qualitymeasuring apparatus according to claim 101, wherein said shield plate isprovided with an upward curl for permitting the shield plate to moveaway when it touches the object, at a corner on the upstream side ofsaid moving path and on the contact side with the object in said shieldplate.
 103. An internal quality measuring apparatus for evaluating aninternal quality of an object thereto, said measuring apparatuscomprising:moving means for moving an object mounted thereon; lightprojecting means for projecting light from the side of the objectthereto, at a predetermined position in a moving path of the object bythe moving means; light receiving means disposed above the object atsaid predetermined position and arranged to receive light having beentransmitted upward by the object; and a tray fixed on said moving meansand arranged to receive said object, said tray covering at least part ofthe object received thereon and having an aperture bored so as to permitthe light from said light projecting means to reach the object, whereinthe internal quality of the object is evaluated based on light incidentto said light receiving means.
 104. An internal quality measuringapparatus for measuring an internal quality of an object on anondestructive basis, said measuring apparatus comprising:conveyingmeans for continuously conveying an object; detecting means fordetecting a spacing between objects mounted on said conveying means;light projecting means for projecting light to the object; lightreceiving means for receiving light having been transmitted through theobject; a first optical fiber having one end located at a position wherethe light projected from said light projecting means can be receiveddirectly and the other end connected to said light receiving means, saidfirst optical fiber receiving the light from said light projecting meanswithout intervention of the object; light amount adjusting meansdisposed at the end or in the middle of an optical path of said firstoptical fiber and arranged to adjust an amount of light passing throughsaid first optical fiber; first shield means disposed at the end or inthe middle of the optical path of said first optical fiber and arrangedto intercept the light passing through said first optical fiber; asecond optical fiber having one end located at a position where thelight emitted from the object can be received and the other endconnected to said light receiving means, said second optical fiberreceiving the light having been transmitted through the object; secondshield means disposed at the end or in the middle of an optical path ofsaid second optical fiber and arranged to intercept light passingthrough said second optical fiber; and control means for controllingoperations of said first shield means and said second shield means,based on the result of the detection by said detecting means; whereinwhile it is determined based on the detection by said detecting meansthat the spacing between the objects on said conveying means is lessthan a predetermined value, said control means makes said first shieldmeans shield said first optical fiber and makes said light receivingmeans measure light incident thereto from said second optical fiber;wherein when it is determined based on the detection by said detectingmeans that the spacing between the objects on said conveying means isnot less than the predetermined value, said control means makes saidsecond shield means shield said second optical fiber and makes saidlight receiving means measure light incident thereto from said firstoptical fiber through said light amount adjusting means; said measuringapparatus further comprising: arithmetic operation means for correctinga result of the measurement by said light receiving means, based on aresult of measurement by said light receiving means when the amount ofthe incident light is controlled by said control means and a result ofmeasurement by said light receiving means when said shield meansintercepts the incident light.
 105. The internal quality measuringapparatus according to claim 104, further comprising measuring means formaking said second shield means shield said second optical fiber at anarbitrary time, irrespective of the result of the detection by saiddetecting means, and for making said light receiving means measure thelight incident thereto from said first optical fiber through said lightamount adjusting means.
 106. The internal quality measuring apparatusaccording to claim 104 or 105,wherein when it is determined based on thedetection by said detecting means that the spacing between the objectson said conveying means is not less than the predetermined value, saidsecond shield means is made to shield said second optical fiber, saidlight receiving means is made to measure the light incident thereto fromsaid first optical fiber through said light amount adjusting means,thereafter said first shield means is further made to shield said firstoptical fiber, and said light receiving means is made to measure lightwith said first optical fiber and said second optical fiber being in ashielded state; or said first shield means and said second shield meansare made to shield said first optical fiber and said second opticalfiber, said light receiving means is made to measure the light with saidfirst optical fiber and said second optical fiber being in the shieldedstate, thereafter said first shield means is opened to open said firstoptical fiber, and said light receiving means is made to measure thelight incident thereto from said first optical fiber through said lightamount adjusting means.